So I finished up my order with troyer and he refused to shut off my rear 02's (o well, I'll live) because I wanted to remove my cats and just get a pipe welded in there. We do not have carb testing where I live and it is not illegal to remove old clogged cats, my truck has 270 k on the original cats. So crystal was telling me how effiecient and non restrictive high flow cats are and that you will lose power by just getting a pipe welded in there. I just don't understand how high flow cats will increase power but just getting rid of them all together reduces power. Somebody please explain this for me. I appreciate it.

 

I cant give you the 100% accurate reasoning, but by installing 2 high flow cats in place of my 4 factory cats gained about 8-10 hp, and the sound was so much better, my exhaust burns cleaner, and it sounds a lot better.

 

well, there is a thing as not ENOUGH backpressure. not quite sure if this is what she was talking about, but that's along the lines of my next mod. going to go with high flow cats and take the gibson exhaust thats on there right now and throw in it the dang river. wayyyyy tooo quite

 

if it were a non diven street truck for drag use he may, but he won't other than that-liability reason with the epa-phil

 

It is a Federal law, not a state law. That means it's illegal everywhere to remove or tamper with the cats. That's why Troyer won't budge. I'd order 2 high flow cats from Magnaflow. You need some backpressure for the engine to run correctly. I cut 2 cats off my 98 (it had 4) & I could tell the low end loss as soon as I left the muffler shop.

 

Cut your cats off and spend $5 on an o2 sim off Ebay. You'll thank yourself for it later. I gutted my 4 cats on my F-150, gained 2 mpg, a ton of power, and a ton of sound.

 

He is in Canada, but I think the same rules still apply. I agree however if you take the stockers off get some highflows. There is no reason to give the smog crowd anymore reason to mandate inspections and make the list of stuff you can do to your truck smaller.

 

I guess every engine acts different. I have extensive mods though, and I flow a LOT more air.

 

Your scenario is a lot different than mine. The laundry list of engine mods is the key to your gains.

 

Yeah up here in Canada it is not illegal to remove clogged or leaking cats and have a pipe welded in place of it.

I am also not worried about smog as I live out on the praries and I can drive for miles down the highway and not see another car on the road.

 

I cut all 4 and freakin did I regret it - no codes or anything . It just sounds like sh^t . I ordered new easterns , they finally came today - there forward cats . I'll be welding it back up next week - can't wait to get that GT sound back..

 

Thinkin about guttin my rears. Local exhaust shop wants $60 a piece to do that....pshh Ill go to the not so legal "kustom muffler" slip the guy 75$ cash and let him do it.

 

stock 4.6 with a higher amount of miles, i think i lost bottom end pull by gutting cats. my exhaust is also raspy sounding up around 3500-5000, with a moderate rumble below that. oh and a tick from the leaking manifold lol.

but im sc'in a 5.4 so maybe the more open flow will help me that time around.

 

not so legal custom shop lol lol. always good to have those guys around. we had a guy up here in central massachusetts that would let you pass inspection if you drove in and your cats were on fire if you slipped him enough cash. hes no longer in bussiness though. undercover guys busted him. ahh the good old days