A friend of mine with an 03 Cobra put bassani headers on his car and lost power. I forget how much but it was proven on a dyno. Why would this happen? They were bassani headers so they weren't cheap. was this because of airflow or something?
go to svtperformance.com
I guess that is a known issue while putting headers on those cars and it kills them. no idea why but I heard that through the grape vine.
Nope, you will gain a lot of power. Its only a wierd issue on the 03-04 cobras. I think it causing them to run more rich,which is what exhaust mods tend to do, and people loose power.