Will I see that much of a gain?
 

First off... I am NOT starting a shorty vs longtube war. I only want good info of if I will gain a decent amount of hp/tq.

My car currently has (installed by first owner) BBK 1 3/4" shorty headers modified to 2 1/2" collectors. It has a Bassani 2 1/2" y-pipe with a quality 3" merge.

I am looking into purchasing the BBK longtube/y pipe kit. They use the same 1 3/4" primaries with a 2 1/2" to 3" y-pipe. So theoretically the only difference between my setup and the BBK longtubes is the primary length. All else is equal.

So...given that, will the extra primary length give me enough of a hp gain to be worth the swap?

It put down 373rwhp with me on a hot humid day. Original owner had it dyno tuned in ohio at the end of october when it was much cooler and it put down 380rwhp with him. I would just like to break 400rwhp with my current setup.

Other mods are in sig.

Everything I have seen shows LT's to make power every time. I think many years ago (when people were doing to hollow log mod) Nobody really gained from shorties. And back then, you could only get Grottyohan Longtubes and Mac middies. I stayed with stock mani's for awhile and made 358rwhp. That was ok way back then. lol

I wouldn't expect your current setup to be making that much more than a stock setup lol...maybe 10hp?

I would bet if you got a good set of longtubes with a 3" collector and a full 3" Y pipe with a good merge, you would be damn close if not at 400rwhp.

Just curious if you dyno'd your car cutout closed through SLP 2OTL vs open as well.

So something like TSP's Pacesetter/tsp y-pipe package should get me close?

I did dyno open vs closed and it was a 5-6hp difference across the board. The 2otl is very free flowing! My favorite catback! Quiet and loud at the flip of a switch.

We have done shortry to long tube swaps on a few cars and seen as much as 20+ rwhp difference but there was quite a bit to be gained overall.

how much over mids?