.... horsepower that you are only going to feel up top...
Yep, I agree.
It was wild for me to see Dawie take a stock 3.2 GTA, remove the stock GTA heads (same size ports, valves and combustion chamber as the 3.0 LS heads) - we'll call them the big heads - and then take the "small" heads from a 24 valve 2.5 with small valves, smaller ports and a smaller combustion chamber, re-open the ports a little drop them on the 3.2 sub and make 15 horses more at the wheels....!
This was running UnChip (which is a piggy-back setup, retaining the stock ECU but modifying the signal a bit) and still retaining the stock AFM and stock drive by wire setup, SMALLER runners from the 164 and keeping the stock AFM setup!!!
The ports were too big for the stock 3.0 24v and even for a 3.2 GTA (which is why AR did not increase them for the GTA) and only start working well on the 3.45. It is only once you get up to the 3.7 that they start to open those ports up on the big heads....
Full-Race 3.7 Litre 24v Milano 6-Speed Getrag; Restored Street/Track 3.0 Litre 24v Milano Verde; 3.7 Litre 24v Turbo Project!