If this is a repeat question (most probably are) I apologize, but have to ask anyway. Is there a power difference between just cutting off the cats and improvising an o/r h pipe or spending the money on the real thing? I ask b/c I have the real thing, but a butthead friend just cut off the cats and swears he lost no power. I really don’t know and most people on this forum are heads above me in knowledge. What is answer? Thanks!

 

I don't see why he would have lost power unless the O2 sensors have lit a CEL.He probably didn't gain a whole lot either.

 

if the cats where cut off and replaced with a piece of pipe. he should gain some hp but if he gutted his cats then the trubulance could cause a loss of hp.

 

Aren't most aftermarket H- or X pipes 2.5" in diameter? That could gain you a little top end, but lose a little bottom end. Basically any exhaust mods done at near stock powerlevels won't gain very many ponies, even if you put full long-tube headers and dumps

 

yeah but a straight 2.25" exhaust is gonna be a lot less restrictive than a catted 2.25" pipe.

 

In stock or near stock trim a catted dual 2.25" will be more than enough.

Without intake modifications or upgrades a stock 4.6 cannot make power high enough to see a benifit form a straight through exhaust vs a catted one. Stock or not you will still lose some bottom end power with a straight through exhaust.

And a stock engine would see more power with LT's installed even if they exit via the stock pipes. LT's make more power from scavenging than flow.