I am not running straight pipes, i am assuming your comment is pointed at roll racer posts in this thread. There will be some restriction being a stock exhaust which will help torque, running catless will just allow the flow to not bottle neck. The advice I have received from the pros I trust, if they say it works, it works.
But I do agree with you if this was a straight pipe application(which it isn't) you would lose any savaging as the pipe would be to short.
But thank you for advice, I will always appreciate the help. The more we share the more we will all learn.

I just meant a straight pipe in that section instead of the round part of the cat where gutted. I know what you mean about exhuast scavenging but I figured that was for naturally aspirated small engines. With turbo engines I always thought better flow yields better turbo spool etc. Better turbo spool means better low end rite?

Yes,you do need to put a pipe in that area,a perferated pipe from a muffler/auto parts store would be ideal, which will help for performance and a non boat sound,,as I mentioned earlier here........

Funny, a Europipe 60mm stage 1 exhaust with 100 cell cats has 2.65 PSI maximum backpressure at 1.3 bar near redline.
Our 70mm stage 2 quiet with 100 cell cats has 2.2 PSI max. backpressure.

Hi ,,,Have you read,,,Modified OEM thread,04-01-2007 and Does anyonehave a dynofor a k24/18 without an exhaust thread,01-11-2011.......It may help,,,Good Luck

I have read the massive drill hole mod post. Some guys i talked to are still running it but some either welded the holes back shut or moved on to an aftermarket system.
Don't think I am going to bother, dont love or hate the factory sound just want to try this first.
I hear there is some hp gain, but most guys did it for the sound change.

Like I said, just trying to help you, with info I remembered....BUT that one thread has Dyno sheets from A/B comparisons and the other is got that guy Porsche Ken that does this for a living......Really,I just wanted to confuse you more........lol........

Ha, thanks your doing a good job i'm more confused than ever but I do appreciate the help with ideas, keep 'em coming.

I know you said you are already doing it, personally I would not. I have 100 cel cats currently and can almost not handle the smell. On an older catless car that I had (mustang 5.0) I would smell like a mechanic whenever I got out of the car from the exhaust smell. Or like I just finished mowing the lawn. I do have a very sensitive nose though and if you haven't noticed it on other cars, you probably won't on this one.

Thanks for the input, yes I have already started, one side gutted. Was this on a 996tt the smell you complain about?
Just about all the exhaust manufactures make a catless system or at the very least sell cat bypass pipes and the ones I spoke with said it's not an issue. Maybe you do have a sensitive nose? I hear alot of cars have this problem but many say these cars don't, so for me I have gone to far to go back so fingers crossed.

My current TT smells a decent amount at idle. It smells rich and like partially unburnt fuel. When I let it cooldown, i cannot pull into the garage to let it idle or it stinks out the garage. It has a fabspeed exhaust with 100 cell cats. I was considering going cattless, but there is no way I could. I just hate the smell too much. It could also be my tune, but I honestly dont know.

Could you shoot some pics while doing the job? It would be very interesting and useful!

Good luck with it..

I am running w/o cats and is not so terrible.

I bought a stock exhaust for 300$ and I am going to do this when the wether brakes. Keep going and post some pictures and results..

Finished gutting, took some pics and buddy has it now to weld it back together. Will post everything after reinstall.
What I can say so far is that this job wasn't all that bad, once you get it open it's a simply pry job to remove all four cats and the two large baffles, they were really quite heavy and the two rear ones by a large baffle were massive.
Took about four hours to remove everything, and the tubing runs through both sides believe it or not. It's not two separate cans they actually connect.
You will go through several cutting disks as the exhaust skin is thick, but not a big deal.
I think it should flow pretty well, removing those cats really opened it up, but I won't know till I install it.
Will keep you all posted.