I remember that test......
www.mach1review.com I think.....
SLP gained 9rwhp, Magnaflow gained 14rwhp
I have seen a gain of 0 rwhp, 5 rwhp, and 12 rwhp with the Magnaflow catback so far on this site......
I have also seen a lot of people having troouble dyno testing the vehicle....
I also know that on the car with 0 gains, they did some computer tuning BEFORE they installed the catback....
I would have to say that you would want to do computer tuning AFTER you install the catback.....
As the idea is if you tune the computer to the stock exhaust, and you change the exhaust, it is actually possible to actually loose hp, never mind having it stay the same.....
I know we do mostly exhaust here, but we do have a very good relationship with Diablo and Edge ( We actually do sell Magnaflow Performance Tuners) so we do know a little bit about tuning as well....
I also saw that on the car with the 5rwhp gain, that they were having troubles with the automatic transmission, so they were not flooring it until a certain RPM, about 3500-4000 RPM if I remember correctly....
That will also effect final numbers as well....
Honestly we have not seen the same gains as on the 99-04 cars, however we have seen consistant gains between 9 and 11 rwhp with the catback....
HP is made mostly in the mufflers in a catback system, you can remove bends or step up the size of piping on gas motors, but most of the hp is made in the mufflers.....
Most companies take universal mufflers and put them in catback systems....
Some companies actually design the mufflers by studying the way the exhaust flows through them on a particular vehicle....ie exhaust speed, wave lengths, and so on......and tune accordingly.....
So basically this is the way we look at it....
On the 99-04 cars we quote 12-14rwhp...
The founder owner of corral.net saw a 16rwhp gain...
On the 05+ cars, we are going to quote 10rwhp, and I have seen one person on here get 12 rwhp....
If we can get gains, there are a lot of other companies out there who can get gains too, becuase most other exhaust companies also have very smart people working for them who know what they are doing....
So I am not going to say right now that we will gain the most, or company X is going to gain the most, because we have not tested every one elses system yet, so we don't know who is making the most power yet......of course we would like to think we are.....
basically what I am trying to say, is that these cars will gain a little power with a catback......
the gains might be dependent upon brand, but it is up to you guys to figure out who is making the most, as I am not about name anyone specifically-
but some systems are definitely gaining more then others- that is all I will say