Hi guys... Just wondering if anyone out there has either removed or hollowed out their cat... Power wise does this make much difference... I got an xforce exhaust and the 200cell cat is flanged at each end so Im thinking bout making up a straight through pipe for drags, dyno days, etc... Anyone got any info on this...? Cheers...

Yep, I have the xforce single 3.5in and had a local exhaust guru make me up the straight through pipe with the flanges for $100 fitted. I have since had the car semi tuned with the cat still out and I would like to think it flows better, how much I do not know but if someone wants to throw money at me for two dyno runs and change of cat (cat is only 10min job anyway, unless your on ramps then a near broken eye socket came my way!lol) I will gladly run my car up and see.

Mine is a 03 BA Auto.

Another thing to replace if you haven't read it on here is the rear muffler to a single straight through as the twin tip is restrictive and was 2-3psi on my car worth of restriction.

Either way I'd say no cat as the noise is marginally different and no one would ever know unless crawling on the ground!

just get a race 100cell cat. they flow 500+rwkw.

otherwise you will fail EVERY EPA emissions test you go to and possible risk of a 10,000$ fine for running no CAT.

But yes, you get big advantages with a hollow cat/hiflow cat.

Does a 100cpsi cat meet EPA though?

Already have removed rear muffler and replaced it with a straight through pipe and made 8-10kw more...

I won't be driving on the road with no cat and I'm pretty sure that u need 200cell to stay legal...

I just wanna straight through pipe that I can bolt in and out for events and the like...

Would it require a retune though...?

just get a race 100cell cat. they flow 500+rwkw.

otherwise you will fail EVERY EPA emissions test you go to and possible risk of a 10,000$ fine for running no CAT.

But yes, you get big advantages with a hollow cat/hiflow cat.

Holy sh*t 10k... Didnt know the fine was that hefty...

I had a hollow cat when I got the BA EPA and I passed with deka 60's, AVO intercooler kit, and I had to swap my hollow cat with a 100cell VENOM cat of ebay. It passed after I ONLY swapped the cat. I still run the VENOM now.

My car is stock BUT is tuned. Would I require a re-tune if I was to replace the cat with a higher flowing cat?

You would need to check whether the AFRs have changed or not. Generally the loss of that small bit of back pressure would mean you should.