MartyJames

About how much could one expect to gain from changing out mufflers on a stock 4.8 assuming the muffler was a 3'' in/out borla xr-1? I know probably no one out there has this EXACT combo I'm just looking for an estimate. I'm still learning about these trucks.

Thanks,
Marty

trever1t

iTrader: (14)

nothing
well not enugh to measure to about 5hp maybe but it will sound a lot better

MartyJames

Really. That’s interesting, so the stocker flows enough then. Thanks for the help.

dirt track racer 81

iTrader: (45)

i bet around 60-120 more hp

trever1t

iTrader: (14)

Headers, mandrel bent Y pipe and free flowing muffler will give you a bit if you tune for it. Just swapping a muffler wont do too much other than sound a lot better. I like the XR-1's, as matter of fact I run 2 of them.

I say doit, it's a good start for a performance truck.

adrenalinep

iTrader: (4)

Like trevor1t said, maybe 5hp at that. They make the stock mufflers to flow pretty good now.

dirt track racer 81

iTrader: (45)

ever cut open a stock muffler? i know the older ones bottle neck down quite a bit inside

00ChevyScott

iTrader: (10)

GMCtrk

iTrader: (27)

I wish I kept the stock muffler and just put a cutout

Bumpers

iTrader: (10)

The only reason to swap the muffler on these trucks is pretty much for sound....you may gain a couple of HP but nothin to write home about. But like trever1t said, if you put some long tubes and tune for them you can gain prolly bout 25hp I would imagine