Despite this discussion on primary cat replacement options, has anyone on here actually done it and are there appreciable power improvement. I already have evom tune, upgraded inter coolers, secondary bypass pipe on my 955 turbo cayenne. Is it a DIY project from under the car to replace the primary pipe with the right tools.

 

No matter the turbo car, a primary cat delete done properly will always net a considerable improvement in HP and TQ. Always worth it as long as you are tuned for it.

 

I know Kent did on his. I asked him about it because with just the secondaries bypassed on mine it smells a bit more than normal. I was thinking of doing the primaries too and wondered if his was pretty stinky with them both gone. He didn't think it was bad.


I would like to eventually do a full 3" exhaust from the turbos back. Too many other things priority right now though.


And yes you'd gain some by removing them. Not sure I've seen a before and after dyno comparison but I'd bet it's a nice little gain.

 

I can weight in. Its been about a week.
Spool is noticeably better. Power feels slightly increased. I currently have EvoMs diverter valves. No tune. I cut welded mufflers and exhaust tips.
Sound is slightly increased at idle. More of a ROAR at Wot.

Primaries are from Hanksville Hot Rod. 02 sensor restrictors were installed on downstream 02 sensors. Restictors were as per Hanksville suggestion installed in most restricted setting. No CEL yet. Readings seem ok.

When doing the job ordered from porsche dealer primary/secondary gaskets. Turbos studs and nuts. All four 02 sensors. 220kms so decided now is the time.

It took me 4hrs a side. Took my time dealing with rust and trying not to break anything.

Not much smell increase but secondaries still in place.

I wasnt thrilled on the idea of becoming a polluter but starting having engine codes. Found a exhaust leak prior to changing at driverside turbo to down pipe from a broken stud. Also passenger side flexpipe was starting to leak. Thats my story. Sticking to it.

Hope this helps anyone making the jump.