I am in the process of gathering information to build my exhaust system. Deadbird and I are talking about y pipe diameter vs. exhaust pipe size. He is going to cut the SLP collector off and put a 2.5 or 3. in flange type collector on.

My engine real quick, 406, 236/242 .550/.560 lift, AFR eliminator 195 heads, air gap RPM intake. Hope to have 520+hp.

I have 1 3/4 SLP's. As I posted in my other post I am wanting deadbird to make a custom y pipe since the collectors are so small and the y pipe is about 2 in. The guy I got the headers from, 87_TA was running 10's with the SLP's and a 4 inch mufflex. 10's I said!!!

After looking at all the cars that run long tubes and the 3 inch mufflex system, I don't see how this 2 inch y pipe works.

Back to my question, which would be best, 2.5 y pipe into a 3.5 system, a 2.5 into a 4in, or 3in y pipe into a 4.

My thinking would be a 3inch y into a 4 inch cat back.

Deadbird thinks the 2.5 y into a 4 wouldnt scavange as efficently as a smaller catback, thats why i suggested a 3in y.

Thoughts? Suggestions?

 

I would think 2.5" into 3.5" would be sufficient.

 

I agree with five7kid. I think that 2.5" into 3.5" would be sufficient also.

2.5" to 4" would not be very effective. 3" to 4" would be good if you had LT's.

 

For ease of installation and room, I think maybe 2.5 would be the better route to go. I was reading in another thread that on the driver side you would have to extent the collector down to clear the steering shaft but without seeing it installed in the car I don't understand that.