Pulling together the exhaust system for the WTF-J (LQ9 w/GMPP "Hot Cam"). I was all set to run a 3" single exhaust, but the tables from Magnaflow, Flowmaster, etc. all suggest that 4" or dual 2.5".

For the moment, my headers run into 2.5" collectors and I am going to merge them before running into a 3" Cat and then out the back. Duals will be more trouble than they are worth, so I am fairly committed to a single exhaust.

Sooooooooooo, what is the right answer?

Thanks.

 

Bump for the morning crew.

Ideas welcome...

 

3" exhaust would be plenty for that setup..

 

single 3" is plenty, i have run 10's on a single 3" exhaust

 

Hey! Thanks to the breakfast club. Build is back on track.

 

i'm using 2.5 from the y pipe out with a 427 LS7 in a TJ and getting 417 rear wheel h.p with a 4L60.---ohhh-- i'm using the stock truck manifolds also----mase

 

What was throwing me was a table that Flowmaster & Magnaflow use that correlates HP to tube size:Given, they're in the business of selling mufflers, so being "conservative" on the tube capacities is a win-win for their sales volumes.

I'm OK now and in the midst of fabbing the crossover for my (Single 3" ) exhaust.

Thanks.

 

pics? Nice engine

I'm using 2.25" pipes into a flowmaster y-pipe and 3" from there into a single flow 44 series muffler on my TJ. Engine is 5.3L.

 

My LS6 powered RX7 had 3 inch headers into a 3.5" pipe. Single exit. The engine lost about 4 RWHP when the exhaust was added. It's about a 400 rwhp engine.

Andrew