High Flow Cat?

[skylox]

Could find anything anywhere, but I was wondering if intalling a high flow cat will cause a MIL or CEL?

thanks for any help

[elwigglero]

Sometimes yes, sometimes no. Get an 02 spacer to be sure.

...or since you're stage 1 APR, get the stage 2 flash which will delete the CEL.

[bigblue]

I love when people ask when they already have software. Ya you can get a free reflash to stage 2 which codes out the rear o2 so no cel. Depends on how far of a drive you have to your dealer I suppose. You could use the spark plug defouler trick as well aka o2 spacer.

[skylox]

ok thanks,
Is it worth getting the stage 2 flash if I dont have a full exhaust? Or should I just wait to get the cat and exhaust at the same time? will i see a difference with just the cat or am i just wasting $$

[teamdaraptor]

IMO there's really no point in doing just a HFC.. You're going to choke the opening back down to the stock spacing anyway. So... if youre at 3" for a HFC, youre going to go back to a 2.5" with stock exhaust.

[bigblue]

Ya you'd want to do the cat and downpipe... the exhaust is not needed as it doesn't really provide any gains. Dyno proven!! At least not on stock turbo. So I would change the downpipe and cat for now.

[billyhoyle]

I love when people ask when they already have software. Ya you can get a free reflash to stage 2 which codes out the rear o2 so no cel. Depends on how far of a drive you have to your dealer I suppose. You could use the spark plug defouler trick as well aka o2 spacer.

Does anyone else's tuner charge a fee for a reflash? The shop here in Calgary charges me $50 for their time, so I can see why some would want to go with the somewhat cheaper 02 spacer.

What's the spark plug defouler trick?

[bigblue]

A spark plug defouler is a part you use to space spark plugs away from an engine and keep them from fouling due to being covered in fuel. So you can get ones that are the same thread as the o2 sensor, you then screw the fouler in the high flow cat or test pipe and then thread the o2 sensor into that and it keeps the sensor out of the stream of exhaust so it doesn't get the full reading on the fast that the cat isn't functioning properly.

[bblume]

youre going to go back to a 2.5" with stock exhaust.

I believe the stock exhaust is 2.25"...that's just what I believe.

[bigblue]

2.25 to the resonator assembly and then dual 1.75.... big enough for ko3 with any mods. Only reason I did mine was because shortly after I went stage 2+ the baffling in the resonator came loose and was loud.

[peta8368]

One of the vendors here sell 200 cell HFC's, and they say that's borderline what the ECU will take (sometimes will throw a CEL, usually not).

So if you go with 300 cell or 400 cell, you should be fine.


Peter

[teamdaraptor]

I believe the stock exhaust is 2.25"...that's just what I believe.

My b5 was 2.25" as well, wasn't sure if they upgraded to 2.5" with the b7, or left it. Sorry.