I am picking up a set of the SSW long tubes for the LSX swap with 3" collectors. Here is my dilemma:

A guy that wrecked his LSX swapped 3rd gen is parting the car out. He had these same headers but the exhaust he was running was a 2.5" x-pipe, ceramic coated, dual (gutted) cats, into a ypipe right at the rear end into a Borla muffler.

What I was contemplating was just buying the x-pipe with the cats and letting him keep the y-junction so I could run duals all the way back. Here's my main concern: Is running a 3" collector into a 2.5" x-pipe going to be taking a step backwards in a negative way? What I'm concerned about is losing the gains I would normally see with these headers because the exhaust is going down to a smaller radius.

Let me hear what you all have to say and then I'll decide. What I was going to do is run the duals all the way back into a knock-off GMMG style dual crimped muffler setup.

 

I would suggest just running a y pipe. IMO the hassle of duals on these cars just isn't worth it. Plus they won't make much over a properly designed y pipe.

 

Well the good thing about this guy's x-pipe is it was already fabbed up with mendrel bent tubing on a 3rd gen, and it runs all the way back to the rear end. So I basically would just have to finish it up with a few more feet of piping.

 

I am running a 2.5 ypipe, to a 3" non mandle bent tube to a magnaflow and made 450 to the wheel. So I am sure that it will not hurt you as much as you think

 

don't forget that the further away from the motor the exhaust gasses are, the cooler they are so they compress a bit. so what i'm saying is the step down is not gonna make any real change in power that matters unless this is an all out race car

 

Not a race car at all, just a nicely equipped street car. I suppose I might pull the trigger on this setup since its only $400...