Ok so here's my delima... I want a dual set up but as of right now I got hedmann shorty headers with a crappy y pipe that was fab'd up and a not so great 2.5" exhaust after the y. My problem is now I have afr195's and cam and hsr intake so I need a lot better flowing exhaust than what I got now. So I also have a set of Doug thorley long tube headers that have the 1 3/4 headers, when I tried to put them on the header would hit the knock sensor on the passenger side. When I got the chip for the set up burnt the knock sensor was taken out. I have seen set ups to where the exhaust is ran down the stock location just as dual pipes with an x pipe and still looked clean. But I know I would probly benefit from the 1 3/4 primaries of the longtubes but I have the auto tranny and run into the issue with the cross member clearance. But I've heard that going from 2.5" 3" out y pipe is just as beneficial for what I'm looking for and needing. I also have been told a full 3" exhaust kills my top end I find that hard to believe?

Can anyone clear up what I should do lol I'm kind of a noob to exhaust so any info helps out a lot I would rather get info that I know is true than from the guys around here that haven't really built a car.

 

If you do a 3 inch exhaust all the way you should be flowing enough for your motor. Those longtubes would probably be fine if they would fit.

 

So do you mean 3" all the way back as in duals or a 3" from headers to a y pipe then 3" all the back. And that shouldn't kill any top end performance right? I should gain quite a bit.

 

Will you hit 180mph? No. Will you lose top end? No. Here's the set up you want to go with: 1 3/4" headers (long or short tubes not a HUGE difference. People will argue that), 3" y pipe, into 3" cat back. A 2.5" y pipe won't kill you, but those work best with the G92 dual cat set up. So 3" all the way

 

Probly not even close lol So the only problem I have with the 1 3/4 headers I already have is they hit the knock sensor on the passenger side so is there a way to take the sensor it self out so it frees up that inch or two of space to allow them to fit. My hedmann's are the 1 5/8 headers so I know I do need new headers lol

 

1 5/8" is not bad at all. Most street cars run them. As for removing the knock sensor, I am unsure. I am still trying to learn what will and what won't throw the car off due to the computer. Someone will know if it will throw a code. I bet it probably would.

 

1 5/8" isn't bad for the afr heads? And well as far as the knock sensor goes it was removed through the computer so nothing will happen if I disconnected it lol I just don't know whats on the other side of it or anything like that lol I know knock sensor just controls spark advance and retard based on what's going on in the engine, and I was told with a cam that would give problems so I had it deleted through the computer.

 

1 5/8" well be fine for you.

 

Ok so with shorty headers that are 1 5/8# 3" inch dual exhaust all the way through would best or the y pipe way 3" all the way through?

 

For your needs 3" dual would not be worth the trouble. A full, single 3" exhaust will flow plenty

 

Lets get some pictures.

 

I had 1 5/8 shorty hedmans with dual 3" cutouts, and ran a 11@124mph.

That exhaust will be fine for you