Catback gains?
I have been sitting on a MAGNAFLOW dual in/out internal x-pipe muffler to replace the rear cats. I will not replace the downpipes with the downpipes Rob sells. I know some of the guys and gals have used this muffler. I then will put the MAGNAFLOW "Y" to bring the dual outlets to a single 3" outlet which will allow for the elimination of the resonator taking the spent gasses into a BORLA PRO XS muffler that has a single 3" in/out muffler. Finding a nice tip to fit the single outlet is important to me and may even use one that quiets the exhaust even more. Possibly put a short round (5")? muffler between the "Y" and the BORLA. I had hoped to try/test Rob's log headers but expense put a damper on that for now.
Would anyone with experience tell me if I can expect a gain of 20wtq/15-19wtq with these mods tuned on a dyno as I never measured the gains from the other engine mods I have for what the car is making from these mods. Hoping for 20RWHP/15-18RWTQ. Likely expectations? Thanks, mark