so i installed part of my exhaust today. i went with the invidia n1 and got a mxp resonated test pipe. got the catback on no sweat. sounds mean, has a nice mellow tone but loud at wot. now for the cat pipe i had a surprise and an issue. first off this was the first real time ive looked under the car. well unknownst to me don herring installed a high flo cat and 3" midpipe. well thats cool because i now have another option. well the issue is the same that everyone has on cat pipes. can not for the life of me get the o2 sensor out. i used a can of pb blaster, let it sit, let it warm etc. i tried a 22mm o2 socket, an adjustable wrench and a breaker bar and its just rounding the hell out of it.

so after that life story of my install what should i do. should i just keep the hfc pipe on the car, stay street legal and sell the test pipe or should i have evodynamics or the dealer try to impact the o2 sensor off and use the test pipe and just swap the cat pipe over for emissions. are the gains going to be worth the money id make reselling the pipe? i mean thats 180bucks closer to the ams downpipe i want

 

Get that HFC out of there and go with your testpipe. A testpipe is easily worth an additional 10whp with proper tuning on a stock turbo car (the more power you make, the bigger gains it'll be worth).

I'm not sure how far along with the Evo X ECU Tephra is, but for the VIII/IX he has hacks that allow you to just remove the rear o2 sensor entirely. Would be worth looking into since it would save you the hassle/cost of having a shop remove it from the HFC for you.

 

I will put another +1 for TP.

 

having had both... I'd say it depends.

Are you having trouble getting the o2 sensor out of the cat or the down pipe?

You might have to get the exhaust hot to get the o2 sensor out. Also you should use an o2 sensor socket (it has a slot in it to make it work with the wires). That might help you get the right angle to get the sensor out. Also if the exhaust is loose it makes it WAY harder to get the o2 sensor off.

And when you do get it off you must use antisieze on it.

 

ya i used an o2 socket and i had it decently warm. just couldnt get the car high enough to get a good seat on the socket and breaker bar. i really might just keep the cat pipe in. i mean 10hp is nice but im not looking for anything special as its my warrantied daily for the next while. i might as well use that 200 towards a new intercooler or the downpipe.

 

I've had better luck with wrenches than those o2 sockets. The sockets seem to always flex (even the expensive Snap-On ones) and round off the sensor.

 

well i think im gonna just keep the cat in. easier with it being a daily driver. dont want to **** off the neighbors to much with the test pipe. so if anyone is interested in a brand new mxp resonated pipe pm me. i got it for 195 i want 195.

 

I have a HFC cat and I'm pretty happy with it. If it was to be used just for track and autocross, etc, I'd go test pipe. But since it's still used for DD as well, I'll just have to deal with the 3% power I'm missing out on.

Just my 2 cents on the matter.

 

HFC sounds good for DD. Also, i don't think RTP will be too loud either.

IMO...TP vs HFC, i would say not just about power...
here is my metal substrate core HFC. ( it's not an evo tho) This HFCs rated @ 700whp ( Ultimate Racing ), and my car ran around 400whp at that time. Idk, how this happend... maybe ran way too rich? or was wayy too hot? Noone knows really...



Just my two cents...

 

The only HFC I would even consider running is the Mil.Spec 100-cell. Also, in my personal experience, I've found resonated testpipes to be quieter than even regular cats.