Ok not for my TA atm but you guys run y-pipes a lot and I do have a y-pipe on my TA.

Ok I currently have 1,1/2" 2.5" ball collectors vette stock headers with a crush bent 2" y into a mandrel 3" with perforated tube muffler.

I am going to 1,5/8" 2.5" flange headers with 2.5" mandrel into the existing 3" mandrel and muffler.

The quarter mile estimated HP is 340rwhp atm. Now dual 2" should be good for 289hp and a single 3" like 339 hp if you use the 2.2cfm per hp. In my opinion the car shuld pick up power all thru the power band with the new y-pipe/headers.

The questions are should I be using 2.25" too y into the 3"?
How much power you think it'll pick up from the bad y-pipe?

I've been over this stuff many times, I prob need more than 3" out, but I'm making what I got work atm.

 

go as big as you can that wont lose exhaust gas velocity.

what you should do is create the smoothest transitions possible. size of the piping is only a piece of the puzzle.

 

I would probably go dual 2.5 into a single 3 before I went 2.25 into a single 3.

 

I was just wondering cause the dual 2.25" has a tad more cfm than the single 3" and that would seem a better match maybe. Still the pieces for 2.5" were cheaper. Also some say a stepped down exhaust flows the cooling gases better.

I bought the 2.5" peices to make the y-pipe, so that's the way I'm going.