If you haven't, do it now, however, don't buy a cat deletion pipe, just have alocal muffler shop make one for you. Mine was only $60 plus $25 for the O2 sensor.

HUGE difference in this car. I've had turbo and supercharged cars, but have never seen such a huge gain from jsut the deletion of the cat. And barely any increase in noise.

 

why do you need an extra O2 sensor?? Isnt there one immediately behind the cat?

 

Hes probably talking about an o2 bung, not the sensor itself.

 

Well the O2 sensor is after the cat, so if you keep the stock cat back section you don't need it.

Sounded like he was only changing the cat to a straight pipe and leaving everything else stock.

 

confused.......if i want to replace the cat with a straight pipe, i have to remove the O2 sensor behind the cat and plug the hole up?? And then remove the O2 sensor totally?

 

Correct, but when going to a straight pipe to delete the cat will eventually trigger check engine lights. So you have to match the ohm resistance to trick the car into thinking it's still there, then the adaptive memory will be unaffected for the factory air-fuel settings.

 

You should leave the O2 sensor right were it is. Deleteing the cat does not remove the sensor. What will happen though is you will get the "check engine light" once you remove the cat. The light does not change the performance of the motor, it's suppose to be a "soft" error and the ECU does not change any functions.

The error just means that the front O2 sensor (just before the downpipe) is reading the same as the rear O2 sensor (the one right behind the cat).

 

60 for the pipe plus 25 for bung = $85 when UR sells one with a cat delete for 75 gauranteed no cel's. You would however have to pay for shipping but it would probably come out to be the same as your custom pipe. What size piping did you use? stainless? if so what gauge?

Jeff

 

BTW,

Several tuners have already posted that removing the cat does very little for the Evo.

 

its good for ~10 wheel horsepower. Thats not negligable to me...

 

Yeah I gained about 10hp with the test pipe. I just did a dyno run yesterday.

 

It's not necessarilly the peak horsepower I'm talking about, I'd be interested to see where the curve is, particularly under 3000 rpms. when driving the Evo stock, it seemed to struggle taking off at normal speed. You really had to give it some gas or it would try to stall out on you. Now, take offs seem effortless. Maybe that is typical of turbo cars, the only other turbo cars I've had were a 93 Talon TSI AWD, and a 225 Audi TT.

all in all, I just thought I'd help get some people off the fence regarding the cat deletion. For $85, hard to beat.

I'll post my 2 cense after VR power kit I and II arrive.

 

I also did before/after dyno runs (within an hour) on a stock car, it too showed about 10 WHP gain without the cat. You could also see the turbo spooled faster 200-300 rpm (better TQ every where), it is the best bang for the buck. A K&N stock replacement is also good for 4-5 WHP on a stock car.

 

High flow cat

About $99 if you shop around. Enough said.

 

id definately be hard pressed to buy a $99 high flow cat, or having a straight pipe for less than $50 (if even 50) if I see some dyno tests, if someone here would be kind enough to post some.

i can get a striaght pipe for cheap. if the performance gains are about the same, id go for the high flow cat. just for convenience reasons.