I am going to effort welding some very short body 400cell cats right to the merge collectors. If it works right, I should have an output flange about where the factory one was, right after the sway bar.

Have you read or tested 2.25" vs 2.5" pipe from the cats back? There might be more selection in 2.5 (and the cat bodies might be shorter), but if it doesn't do anything worthwhile, I'll make up a new midpipe with the Borla in it at 2.25.

Hey hey... I got my headers bolted up, and the guy that welded the forward O2 bung into the collector was eyeballing it. The forward sensor touches one of the rear primaires when it is in. Not enough to keep it from threading, but it is still touching.


Is that a deal breaker long term? What about short term--can I run that way long enough to get the kinks out of everything else (and see if it is going to run at all), or should I relocate it?


There is tons of space between the collector and the skid plate down by the engine. I could just drill and weld a new sensor bung on the opposite side of the collector from below. But that might require pulling it back off, which is annoying.

Bummer. It might be fine to run as is. It's no fun to pull them once their in. If heat isn't an issue on the contact spot on the sensor, run it. Maybe a thin piece of aluminum wedged in between to act as a heat sink/shield. You can also maybe back the tension off the header header studs to maybe get a little wiggle room. Just shooting some ideas.

Did you weld up some cats off the collectors? Send a picture if you can.