finally got the motor out of my car and it has Flowmaster ex. from cat back which is 3"( single pipe) the mods I am doing are GM 847, rebuilding to 355 and bumping compression to 11:1, ported heads w/ 2.02/ 1.60,Hooker headers and bolt ons. My question is that I did the math comparing dual 2 1/2 ex compared to headers to 3" y and 3 " back to muffler then back to dual 3". Theoretically to flowcomparable to the dual you need 3 1/2 single pipe. Are people making 400 plus rwhp through 3 in single. My goal is 400 to 425 and would like any input.

thx,
jonesy
niles, mi.

 

Single 3" should be good for a lot more than 400 rwhp...

 

You could make 400rwhp with a single 3" catback, but it will probably be a restriction. When I went true duals, I felt a SOTP gain, but for all I know its in my head. I haven't felt a SOTP gain from a mod in awhile, this is something I'm pretty sure i feel though. I'll know for sure when I get on a dyno for a dyno tune.

 

where can you get TRUE duals ? do both pipes run where the single did, then split off after axle?

 

My buddy rolled 420ish with a le2 383 through a 3 inch pipe and magnaflow muffler so it is done all the time, If you are looing for more than that then the 3 inch pipe will start to be more of a restriction.

 

I agree with the above post. Sure the 3" will do it but you are leaving power on the table. At that HP level you should be thinking of a 3.5" system.

 

thx all , I can rest now , just wanted to confirm that I felt that the 3" would restrict it. Try to slide local muffler shop some cash and run true duals minus the cats

 

On the dyno my car put down identical numbers through the 3" system with a magnaflow muffler as it did with a 3" cutout. Take that FWIW but if you can do 3.5", I don't think it would hurt other than starting to limit your options on mufflers.

 

Magnaflow has come out with a very nice 3.5" muffler. It is part number 12909. It is of the straight through design for high flow but suprisingly on the quiet side.