Downpipe
 

Been looking into a couple after purchasing my Invidia Q300 Cat-back, I dislike the fact that the downpipe looks restrictive. I was looking into either Cobb: Single cat DP Bellmouth, Perrin: Single cat w/ Divorced Wastegate, and an Invidia: Single cat Divorced Wastegate. I realized that an AP tune is necessary to ensure the vehicle runs properly, no shortcuts here. Whats been bugging me is the fact theres a few bit of pros and cons. The Cobb Dp has a cat after the O2 sensor, though they carry an AP with a tune to run along side their DP. Perrin suits me to where the Cat is before the O2 sensor along with the Invidia. Perrin also does sell the AP in addition comes along with a free custom map and that does sound like a deal. I am a bit anal about the Cat placement vs O2 sensor. I'm curious that once I flash the ECU with the AP would it prevent a CEL?

I've heard of welding on cheaters that extend the O2 away from the piping in order to run it without tuning anything. Im not considering that at the moment. Though injen makes a catted downpipe with it fabricated on. So if anybody has any experiences with that please share. I'd like to hear what you would go for.

I dont see it listed but I have an invidia bellmouth high flow that is a good quality piece....

Do you like to tinker? If so why not just go catless as you will not have to smog for 5 years, and then when its time just put the stocker back on as it is pretty simple to do....Plus catless is cheaper.

I guess, but I dislike the smell of un-catted exhausts. I was told the q300 would eliminate whats left of an Un-catted DP. But I don't know, he recently just fried his ECU.

i also have the invidia catted, have had zero o2 issues. with the cobb OTS (off the shelf) stage 2 map, the o2 CEL in question will be turned off. so don't worry about it, and you'll get great gains from adding the DP and going stage 2.