if your not using FI, 4XX motor, or 1XX+ nitrous i really don't see any reason for dual 3" piping.
big pipe = big noise
but thats just my opinion.

 

So the poll is leaning towards 2.5" My Y pipes are 2.5" He will just have to cut the spot where it Y's in to collector. I am sure he can expand the 2.5 to the 3" muffler.

If 2.5 can support what I have/could have with room to spare, I will contact the muffler shop tomorrow.

 

I don't see a real need for true duals and a cammed engine, w/ stock heads. IMO, a 2.5" true dual setup isn't going to outflow a single 3" exhaust setup. And a single exhaust run is going to be cheaper.

IMO, 3" true duals < 4" single.

My setup: 1-3/4" LTs, ORY, SI/SO chambered borla xr-1, corsa 3"-3.5" tip. Flows its *** off. Could be had for less than $1k, depending on what you want to run.

 

I did this with mine no problem. OBX long tubes, cut the Y pipe and the braces and put an X-pipe in. came back a little more with the 2.5" and then changed to 3" for my mufflers, and then finished 3" back

 

i gained across the board with true dual 3". mostly down low. this is with 1 7/8 stepped to 2" headers and budget heads.

 

I have 3" true duals. And like it. MAke sure you have en put a cross over or h pipe in. If you run true dual

 

Did I read that right or was that a typo..."2.5 duals will not outflow a single 3" .
In my feeble mind, 2.5 duals = single 5" pipe, 3" duals = 6" pipe.

This Magnaflow has an X built in. But for good measure I can have the exhaust shop put one in.

 

Come on man, you're joking right?

Go with true duals, I'm sure you'll like them.

 

2 x 2.5 pipes outflow a single 3"
2 x 3" pipes outflow a single 4"
and a single 5" outflows 2 x 3" pipes

 

If you compare strictly the cross-sectional areas of the pipe, a dual 2.5" set-up will have 9.8175 in^2, a single 3" will have 7.0686 in^2, dual 3" will have 14.1372 in^2, and a 4" single pipe will have 12.5664 in^2.

Granted, its not quite an apples to apples comparison among them due to the dynamics of the gas through the pipe (heat, behavior of the gas near the pipe wall, etc) but its a rough comparison for discussion's sake.

But in short, yes, it can be safely assumed a dual 2.5" will outflow a single 3", and a dual 3" will outflow a single 4". Now the effects of one size versus another is a whole other conversation.