High flow cat

[Blue9N3]

Wondering whether to get a high flow cat (already have a 3" dump, straight through rear muffler, fmic and apr tune). Will it make much of a difference?


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[h100vw]

Wondering whether to get a high flow cat (already have a 3" dump, straight through rear muffler, fmic and apr tune). Will it make much of a difference?


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If you already have a downpipe, What cat is in that??

[sambb]

If you have a stock cat then an aftermarket high flow cat will make a difference because it isn't chock full of over a decade of crud and its matrix is so much less dense than the stocker that you can see through it. When you get it welded in have it positioned as far back along the pipe work as you can. By moving the first restriction that the exhaust gasses see as far away as possible, you'll delay the onset of back pressure ramp up which will really help spool up, response etc etc. not ideal from an emissions point of view though.

[Blue9N3]

3" dump into stock cat. Dump made a big difference. Just wondering whether changing the cat will.....


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[h100vw]

Swap out that std cat. 800 cell v 200 cell. Very different flow. Don't cheap out

[Blue9N3]

Not a 100 cell?


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[h100vw]

Not a 100 cell?


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The difference is small but 200 would likely pass an emissions test

[TDIfan]

The difference is small but 200 would likely pass an emissions test

Don't think there is an annual test in WA
Only have to do it if you get a yellow sticker from the boys in blue

[Blue9N3]

Update: Ended up getting a 100cell and one of those spacer things with the mini cat just in case put in by an exhaust shop.
Result: surprising improvement in response and overall grunt. No codes no errors on APR V2

Bad: car got quite a lot louder..... (have a straight through oval muffler at the back). Right on my threshold for tolerance... (might be something to do with the fact that I'm over 40...)


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[sambb]

The cat is the first thing in the line that will build back pressure so the freer flowing and further back you can fit it the better. Yeah they can get barky can't they. I'm 3in dump into 200 cell, and then straight piped all the way out after that. Even with the rear section being 2/1/4in its loud when your on boost. It crackles and pops too without the muffler. Its forcing me to play my music louder so my 40yo ears are going to go downhill even faster now.

[Blue9N3]

Glad to see I'm not the only oldie with a 9n3 gti.


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[LZY13B]

I have a custom 3" dump going into a milteck cat not sure what cell it is and the rest is standard and I was disappointed that it still sounds standard and is too quiet haha

[sambb]

Do you still have the stock muffler because if you do, that is the culprit. Its a horrible design that puts gases into a dead end and forces all the gas out through louvres into an outer chamber that the twin tail pipes come from. Its very quiet and flows horribly. Seriously cut it off and get an exhaust shop to weld on a single straight pipe and just run sans muffler. Its civil in traffic (it'll crackle a bit on over run) and fires up when you are up it even if you have the centre resonator (early models) and you'll notice a jump in power. I can only vouch for a 2/1/3 tail pipe out the back though. If you tried 2/1/2 straight through it'd rattle your ear drums then I think.

[LZY13B]

Mine is a early model it's a December 05 model so it does have the resonator so might have to look into changing the rear muffler to get a little sound out of it and hopefully better flow

[ZR36]

So i have my R36 booked in to get the centre suit case out replaced with a straight though pipe. Should i get the cats changed over to hi flow while im at it?