LuminoZ

Where I live there are no smog emission regulations. I know that punching the catalytic converters isn't the coolest thing to do right now so please don't flame for that.

My question is simply this:

How does the 3.4L respond to installing performance headers (LC egr.) and punching out the cats and running a URD o2 sender?

I'm worried about burning valves and whatnot from installing all of this...

Elton

not very good unless u got a super charger

mjwalfredo

I am no expert but from what I have read in other posts, it sounds like the performance boost from headers is not worth the cost on a normally aspirated 3.4. If you have a supercharger, a freer flowing exhaust will gain you some serious performance.

turboale

Not to mention its going to stink...

If you don't have a body lift don't bother with the headers. I have heard they are a huge pain to install w/o a body lift and now hearing the gains w/o an S/C are minimal there is another reason... Also stay away from the TRD headers. They are very soft and leakage problems are pretty common. Espcially when people over tighten to try to stop the leak when in reality they are doing nothing but making things worse. I would get a race cat and call it a day, that way you get better flow and your truck won't smell like a burning gas station...

RunnerUp

but burning gas stations smell awesome!

on a side note... dont go no cats and headers, do you want to go deaf?

turboale

You should hear my truck... Somehow Greddy managed to turn a muffler into a megaphone... Its not my dd so I don't mind, the power gains are just too great to put the stock system back on.

RunnerUp

turboale are you SCed?

olharleyman

Anyone know if I need a body lift for a 2nd gen 3.4 s/c swap for the headers?

Nate08

I've heard losing your cat makes performance worse on the 3.4. On a Chevy it's different. IDK, don't ask why losing cats makes it worse on a 3.4, i dont know. Just get a Magnaflow HighFlow one. Headers are too much of a pain for the 3.4. Not enough power to justify the money and time and effort. Plus you always gotta worry about blowing a gasket.

SHONUUP

I'm currently running downey headers with no cats and a magnaflo straight through design muffler with a baffle and the performance on the highway was quite a gain. i didn't really notice the 0-60 performance but after 60mph the increase seems to be more noticeable according to my butt-dyno-meter. As far as the loudness...it only sets off car alarms when i rev it up on drive bys... but at normal crusing speeds and idle it sounds pretty good. I'll try and get some sound clips up soon if anyone is interested...

but the smell is "gassy" w/o cats....

YUonDAGround

I'll tell you this, I took the cat off of my NON SC'd 4Runner and put an O2 simulator so I wouldnt throw a CEL. I noticed imediatley that the performance was worse and my gas mileage dropped about 40 miles to the tank. Something about the back pressure and the way these engines were designed. If you have the extra money to spend for the headers and SC try it without the cat and with the cat to see what the performance gains are between the two setups and report back with your findings.

Bruce

X-AWDriver

Or just buy a high flow cat for $100 and still be green and still get the same performance gain you'd get from no cat.

I wish people had strip numbers to compare to their butt-o-meters since the gains you think you might be getting aren't as grand as one thinks they are. Loud exausts seem to transmit the feeling of power to people asses in alot of cases.

Headers do help but the gain is no more than a maybe 5whp on a NA 4Runner so spending several hundred bucks to see virtually nothing is not my cup of tea but if I had a deep wallet I might do that AFTER an SC.

SHONUUP

Haha.. i agree. plus the smell is really strong w/o the cat. I'm tempted to put a hi-flow back in just because of the smell.

But i gotta say, my 4runner's exhaust sounds pretty sick!

DN1911

I am currently running no cats on my 01'. but it was done the right way. you can't just hallow out the cat and put it back on. this creates an expansion chamber and slows down the exhaust flow. the cats need replaced with tubing or a sleeve thru the old cat body. this is how i did mine. there seems to be increased throttle response and performance, but it does smell like an old carbed car. as far as fuel mileage it is down right now but that may be do to weather. i am waiting for it warm up to test that theory out. i would have put in high flows but didn't have the extra cash. i did all the work and only cost about $75, that was for the simulator. the wife says the simulator is causing a super faint clicking noise in the dash that i can't hear very well. i kind of wish i would have used Empire Performances plug-in sim so that there would not of been and cut & splicing.

mt_goat

Yeah I'm pretty sure my bicycle was faster when I put cards to flap in the spokes.

LuminoZ

So if i install magnaflow hiflow cats, will i still need the URD sender?

mt_goat

You mean the URD simulator? Probably....maybe if you get those expensive OBDII cats for the Calif market you won't, but those cost like $500 each.
http://www.car-sound.com/02product/d...niversal=43006