New 3in Exhaust(want to have tuned by frost)

[smkn gts]

Hey guys,

I have a quick question, I recently had a 3in stainless magnaflow exhaust installed from the manifold back with an electric cut off right after the ory pipe. The exhaust sounds great but there is no back pressure what so ever. My friend with a ws6 seems to think that the lack of back pressure is actually slowing down my car in comparison to the stock exhaust which I dis agree. He says that because other than the lid the car is stock the car needs the back pressure and he thinks i should try a restrictor pipe to see. I dont know if it is a tuning issue but I know the car has a check engine light on as well. I know it sounds like a silly question but could the exhaust really be affecting hp? and would a tune fix any of these issues? I know the computer can greatly affect how the car runs and I was wondering if the computer needs to be tuned for the change from stock to such a large exhaust system!


I think I will post this in the bolt on section of this site as well!

Thanks for reading

[blkSS98]

I'm pretty sure someone said "the lack of backpressure arguement" is a myth. I installed a borla 3" exhuaust on my SS, and my check engine light is not on. I would try the simple things first like, cleaning the MAF, maybe replace your o2's, or it could be because you put an ory on a car that hasn't had it rear o2's tuned out.

[stew215]

The back pressure argument is bull. My truck has a 396 with custom headers into a 4 inch collector with duals/dumps. The truck runs just as good if not better with the dumps open. I have not had it on the dyno to confirm this but many people on here have noticed around a 5-10 HP gain from opening cutouts. So in my opinion pack pressure does not matter.

[stew215]

This passage is from magnaflows web site .... The lower the backpressure the more performance.



"
Some stock mufflers and exhaust systems have up to 18psi of choking, power-robbing backpressure. In direct contrast, a well-designed, high-performance street exhaust system typically has about 2 to 6 psi of backpressure. For an interesting comparison, an un-muffled straight pipe on a real racecar usually has 1 to 3 psi of backpressure. "

[smkn gts]

Thanks guys, I thought this was true about the back pressure being a myth but now i am just wondering if a mail order tune help my computer adjust to the new exhaust and even add a few more ponies