High flow cat

[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?

[Blue9N3]

I did mine in 3 stages (saying each time, this is the last). Dump pipe, rear muffler (straight through oval) and then high flow cat. Each seemed to make a noticeable difference. Dump and cat - better response and top end. Rear muffler, better top end.


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[ZR36]

Any error lights after each change? Brand of cats you installed, and cost?

[sambb]

With our cars if you are on a standard tune or a stage 1 generally and you swap in a high flow you could get an error. A 200 cell maybe not but a 100 cell almost definitely. Initially I'd fitted a 200 cell and dump pipe whilst still on a stage 1 tune (that didn't ignore the cat sensor signal) and had to use a right angle fitting between the cat and the second sensor to avoid the code. It basically stands off the sensor and orients it so that it only gets a sniff of the real exhaust flow and tricks the ECU into thinking that all is good. It could be that your car doesn't have these fitted in which case you're laughing. The fittings don't cost much- maybe 30 bucks each, but there has to be room for them and the angle they put the sensor at. For performance, high flow cats will help yeah. I'd say go 200 cell to be on the safe side. If you get errors then get the stand-offs fitted - just make sure that the cats that are fitted have the bungs oriented so that you can fit them once they are welded in.

[ZR36]

Im not keen to spend 'turning money' on something im not going to be keeping long term. i would rather get myself into a new toy. And i need to get my roof lining replaced before i sell it.

[Blue9N3]

I got the spacer with the mini cat inside just to be sure. The spacers alone are about $7 on eBay, the o2 ones around $50?


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