I have to say that I wasn't to impressed with MSD. I had a MSD Dis-4 in my car and the dang thing fried after 4 months of use. After surfing the MSD Tech Forms I found that I wasn't the only one who had this problem either.
The MSD tech recommended that the box should not be placed in an enclosed area that it needs air flowing over it.
Have you ever watch Nascar? Ever wonder why they have 2 MSD igniton control box's on the
dash.................so if one fails they can easly switch over to the other one.
I think that one needs to consider the placement of whatever ignition control box they get. There is quite a few race heads that say the engine bay is too hot for the ignition control box and they should be placed inside the car.
I didn't buy another MSD I went to an Autronic 500R CID instead. I'm running a direct fire ignition (one coil per cylinder) so that limited my choices for a replacement ignition. I feel I have the best ignition system for my set up with the Autronic 500R CID.
I also built a cool tunnel for it to keep it cool.
Here are the spec's for the Autronic 500R CID for comparison.
http://www.autronic.com/page_files/direct_fire_cdi.htm