[RoryJ]

What does everyone think of the Centerline SZ-style headers for our cars?

SZ Headers GTV/6 and Milano | Centerline International

Centerline International is the leading supplier of restoration, performance, and maintenance parts for all Alfa Romeo models fr

centerlinealfa.com

Have had great experience with Centerline in the past, but does anyone have hands-on experience with these? Will probably run them straight back to a Stebro rear section with a custom center pipe. Is "aluminized steel" a durable material, or are these likely to rot out sooner than later?

On my 3.0, I'm currently running a stock exhaust with catalytic converter back to a Stebro exhaust. If I'm honest, sound is the thing I'm mostly after, but a few horsepower wouldn't hurt either! If sound is my only consideration, should I just replace the cat and resonator with a straight pipe to the rear section (non-smog state) or is it likely I'll get significantly improved tone with these headers?

My first 2.5 Milano Platinum years ago ran a Shankle system straight back to an Ansa rear and sounded amazing. I've got a NOS Ansa rear section on the shelf too that I could run.

CSC system sounds great from what I've heard, but too much money and too little ground clearance (plus recent quality control issues have me worried).

Thanks,
Rory

 

[alfaparticle]

CSC ground clearance is OK as the 6 pipes are in a horizontal line. IMO they are very good. I got a good price on them from EB Spares in the UK.

 

[Gubi]

If you're running stock fuel injection those only have a lambda sensor bung on one side, which isn't great since you're only sampling one side of the engine for the feedback loop.

If I were spending the money I'd probably get the Magnaflow downtube/cat setup that Centerline sells. Has the lambda sensor bung in a better place, has a high flow cat for better performance, and doesn't violate federal emissions laws (even if you're in a non-smog state, it's not legal to remove the cat converter on a street car. Not saying you'll get caught but legit shops won't install parts that do that, and could cause issues if you ever try to sell it out of state.)

When I had my Milano I kept waiting to fail smog so I could justify getting the new cat converter setup, but the **** thing passed every two years with flying colors.

Exh Front GTV/6 Milano | Centerline International

Centerline International is the leading supplier of restoration, performance, and maintenance parts for all Alfa Romeo models fr

centerlinealfa.com

 

[RoryJ]

CSC ground clearance is OK as the 6 pipes are in a horizontal line. IMO they are very good. I got a good price on them from EB Spares in the UK.

You're right, they're a bit cheaper there than in the U.S., it seems. Thanks for the tip, still a few hundred more than the SZ system, it appears. Do you notice any problems with just having the lambda bung on one side as Gubi referred to?

If I were spending the money I'd probably get the Magnaflow downtube/cat setup that Centerline sells. Has the lambda sensor bung in a better place, has a high flow cat for better performance, and doesn't violate federal emissions laws (even if you're in a non-smog state, it's not legal to remove the cat converter on a street car. Not saying you'll get caught but legit shops won't install parts that do that, and could cause issues if you ever try to sell it out of state.)

Exh Front GTV/6 Milano | Centerline International

Centerline International is the leading supplier of restoration, performance, and maintenance parts for all Alfa Romeo models fr

centerlinealfa.com

I've seen that, thanks. Not necessarily opposed to running a cat (I am currently).

I don't really care about another 5-10 hp, to be honest. My primary consideration really is sound at this stage. A while back, I had a local well-known shop replace my rear section with a Stebro I had laying around, but I'm unimpressed with the difference in tone and volume. Maybe I just need to have a muffler shop eliminate the center resonator between cat and Stebro? What will uncork my Busso?

 

[Alfistaa]

Since you asked:
Problem with both types of headers is the O2 sensor is only on one side of the engine. This is suboptimal because it can lead to erratic fuel mixture trims and bad engine response at lower rpms. If you decide on installing one of these header pipes you should either omit both the O2 sensor and the cat, or install a Magnaflow cat with two inlets/outlets and an O2 sensor. Although I would go with the later option to stay within the law, omitting the O2 sensor and cat may be a tad better for performance as the computer will run open loop based on a predetermined fuel map that is probably a tad richer. Better for performance but worse for MPG.

As for sound, I think you answered your own question. No center resonator, Ansa rear muffler.

 

[alfaparticle]

My reason for buying CSC headers was performance. The car made 214 HP at the wheels. It also sounded good. I was at a track day and a Corvette owner told me that I had the best sounding car there. Exhaust was 2.5" to a single straight through Borla muffler in the rear position. I had no problems with the Lambda signal which fed into the Megasquirt engine management computer.

 

[Mark_toro]

Never had a problem with a single O2 in one branch. This is a batch fire system, and not that sophisticated. Yes it is sub optimal, but isn't there compromise in everything?

Staying within the law - you would think that would be cut and dry, but if you modify the car at all you are likely in violation. If you are reasonable, and don't have annual smog checks in your area, you will likely never have a problem. "Rolling Coal" or very loud exhaust and you are seeking violations. I wouldn't ask my mechanic to make illegal modifications, but I have never had issues with them working on my modified cars - legal or otherwise. Resale is another area of difficulty. Even in Nebraska it is illegal to sell a car that has been emissions modified. That doesn't mean that it doesn't happen, The letter of the law and what is enforced are often very different.

Best plan in this area is: Fly low, fly slow.

 

[Gubi]

Staying within the law - you would think that would be cut and dry, but if you modify the car at all you are likely in violation.

Yeah, no. The front exhaust with cat that Centerline sells is perfectly legal in all 50-states. Any exhaust mods aft of the cat are legal (at least from an emissions standpoint) as it doesn't impact emissions, just sound.

 

[Mark_toro]

Per Centerline web site:

"Part #PH120C
Headers GTV6 and Milano with Cats
Performance Headers W/ Cats GTV/6 and Milano
Performance Headers for GTV/6 and Milano 2.5 and 3.0. Manufactured for Centerline in Italy. 100% stainless steel. Unique design gives great high RPM power with much better ground clearance than other header systems. Flex pipes installed in downpipes prevent header cracking.
Includes dual, high-flow catalytic converters. Cats are not California-certified."

So unfortunately, they are not 50 state.

Here is where it gets more confusing. CARB is the only organization that grants executive orders for aftermarket parts (EPA does not certify or allow alternate parts, except direct service replacement). Basically if CARB provides an EO for an aftermarket part, EPA will accept it, although I have not read this in the regulations. If there is no CARB EO, then the component is essentially not legal anywhere in the US, unless it is a direct service replacement. Last time I read the regulations, EPA was pretty clear cut on no modifications. Been a while, so thing may have changed some.

Enforcement of all this confusion is another layer entirely. In most of the US, if you are not obvious or obnoxious no one will bother you. Then there are the "safety inspection" areas. If things look neat and clean, or you have a CARB EO, you will be fine. Then there are the "sniffer test" areas, where you may have to prove some type of performance (relevant to real world?). Finally there is California

 

[Gubi]

Again, no: that's part PH120C and is not what I was talking about. See my link above, the Magnaflow OE561 is 50-state certified.

CARB EOs are a requirement for cats sold in California. A couple of other states (Maine & NY, apparently) require CARB cats only for CA-emissions certified vehicles later than a certain year (2001 and newer Maine, 1993 and newer NY).

EPA Compliance - Federal and State Emissions Standards | MagnaFlow

Where your vehicle is registered will determine what type of MagnaFlow catalytic converter you’re legally permitted to purchase, install and use. To learn more about government regulations around emission standards in California, Maine, New York or all other states (Federal), please see these...

www.magnaflow.com

Important Notice for OBDII Vehicles

To prevent a recurrence of emissions-related problems, the following steps should be taken prior to replacing a converter on a vehicle equipped with an OBDII system:

www.walkerexhaust.com

For the rest of the country a CARB EO is not applicable and the converter just needs to meet federal/EPA standards.

 

[RoryJ]

Guys, really appreciate all the input and the discussions of legality are interesting. I currently live in a county in Washington state with no smog testing (and how sweet it is, having lived in California most of my life!) but eventually all of WA is going to ditch smog testing, looks like.

I found a deal from a Magnaflow supplier for the 49-state Centerline/Magnaflow high-flow catalytic converter system: $340 shipped. I'll find a good local muffler shop and have them join that to my stock cast iron manifolds, then build a center Y-pipe to link the cats straight to my NOS Ansa rear section, effectively deleting the middle resonator. Sounds like that should give me amplified volume while keeping the car legal in most states and not too loud. If I get a bit of a power gain too, great. Doubt I'd really even notice an extra 5-10 hp.

I must just like the Ansa tone more than the current Stebro I have installed.

 

[Gubi]

Woo, that price is a steal.

Dunno how it'll sound, but I'm the wrong guy to ask. I always thought the Milano sounded great stock. When I got mine it had an Ansa rear muffler that I replaced with stock because I found the loudness annoying 😆

 

[alfaparticle]

If the Confederate EPA ever gets interested in this stuff then the guys riding Harleys with straight pipes should get nailed before us.

 

[RoryJ]

I'll take some video once this system is installed and provide a link here for sound. This is where I ordered from, 20% off, free shipping and no sales tax: Magnaflow Exhaust Solutions Sale is still going on, apparently. Only downside is that my order confirmation email says the system is in queue to be built isn't likely to arrive until October, but I'm in no real hurry.

 

[Del]

We tried an Ansa rear muffler on our 89 Milano, and also found the resonances at certain rpms very irritating. The Ansa didn't last long on the car, needless to say. Alfa spent a lot of money on the exhaust systems of their models, previous to the Giulia/Stelvio, to sound very nice without being raucous or having that resonance at cruise rpms/speeds.

 

[RoryJ]

We tried an Ansa rear muffler on our 89 Milano, and also found the resonances at certain rpms very irritating. The Ansa didn't last long on the car, needless to say. Alfa spent a lot of money on the exhaust systems of their models, previous to the Giulia/Stelvio, to sound very nice without being raucous.

I'm sure that's true and I respect your long-term Milano experience, but I enjoyed the tone of the Ansa system on my previous Milano Platinum very much. My current Verde is purely an occasional weekend toy, accruing under 1,000 miles per year at this stage. When I drive it, I want to hear it.

 

[Del]

The car sounded ok for most of the rpm and throttle range, but at certain rpms, usually at a cruise speed in each gear, alas, there was a resonance which both of us found to be just plain irritating. Very un-Alfa and a shame, as the muffler tips looked fine (although I've found in the past that Ansa mufflers didn't seem to last very long, rusting out, thus always returning to stock). I even installed some expensive soundproofing sheets in the trunk and under the rear seat, to no avail. We just didn't want to drive the car much, even if we've been driving nothing but Alfas since the mid 60s. Your choices are certainly your own, and that's fine. I was just indicating that for us, for long term satisfaction and hearing peace of mind, stock always turned out to be most satisfactory regardless of whatever model we owned and drove. It was just one of the true Alfa characteristics.

 

[Brendan_LS]

If you're running stock fuel injection those only have a lambda sensor bung on one side, which isn't great since you're only sampling one side of the engine for the feedback loop.

If I were spending the money I'd probably get the Magnaflow downtube/cat setup that Centerline sells. Has the lambda sensor bung in a better place, has a high flow cat for better performance, and doesn't violate federal emissions laws (even if you're in a non-smog state, it's not legal to remove the cat converter on a street car. Not saying you'll get caught but legit shops won't install parts that do that, and could cause issues if you ever try to sell it out of state.)

When I had my Milano I kept waiting to fail smog so I could justify getting the new cat converter setup, but the **** thing passed every two years with flying colors.

Exh Front GTV/6 Milano | Centerline International

Centerline International is the leading supplier of restoration, performance, and maintenance parts for all Alfa Romeo models fr

centerlinealfa.com

when I built my own exhaust, I basically copied one of these magnaflow pipes - just without the cats. I used a tapered cone right after the downpipe flange to enlarge to 2" right away, then two good quality flex pipes and then a home made H-pipe right underneath the guibo hole withe the 2 sensor bungs (one for tuning and one for the ECU). two very large magnaflow mufflers complete the system - the dual 2" downipes combine in a dual in single 2.5 out chambered muffler, and then a large 22" long magnaflow at the rear. I like my cars quiet - until my foot is down and this system does just that. the stock manifolds got taken to with a single cut burr to match my head porting and I called it good there - no power to be gained in spent gases - just watch that engine masters video.

 

[racingswim2006]

For sound reference, this is the Centerline SZ header set, no converters, Stebro center section, straight pipe rear:

It's loud but sounds awesome. With the Stebro rear installed, it still sounds really good and is streetable.


For other reference: I have installed and run these Centerline SZ headers on a few different cars. They are pretty nice actually. Much easier to fit and deal with than CSC, and don't hang down as low.