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maneesh

De-cat, Pre-cat Removal, Straight Thru Pipes, I'm Confused!

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New to the modding game, but catching up as fast as I can :duh:

After fitting Blitz filter, it does pull to redline, but there seems to be a sticking point around 4k revs where it feels like there is a blockage in the system, possibly backpressure problem.

Someone said I should de-cat, another said take out pre-cats, also someone mentioned straight thru pipe.

My new back boxes still have to go on, so I might as well get the garage to mess around with the cats to try and get it pulling smoothly again.

My question is what do you lot recommend I do with regards to the cats? If you take out main cats or pre-cats, I'm assuming you get more noise and performance, but is the noise minimal at light throttle (i.e. when cruising)?

Thanks guys!

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Just a quick check mate, but you did reset the ECU after you'd fit the new filter?

Removing the precats shouldn't be too bad if it's like the IS I guess, but as for the main cat, removing that can be complicated as you'd probably need O2 simulators and stuff otherwise the car will keep throwing CEL's

There has also always been debate on the IS over whether the removal of precats actually does make any difference - some say yes, some say no, I never had mine done so can't honestly comment!

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Just a quick check mate, but you did reset the ECU after you'd fit the new filter?

Yes, that helped a lot, then put part of the old factory airbox on, which helped too. Need to build cold air box too, as the air is too hot right now.

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Yeah big time mate, when I had my induction stuff on even with the cold air box the difference was night and day between driving on a hot day and driving on a cold day - it's where you realise the pros and cons of an induction kit as opposed to the standard system.

Guess at the minute even with the cold air box you're not actually getting cold air - it's still the warm air from outside the car, just not as hot as the red hot air in the engine bay :lol:

Personally on your car I'd leave your cats intact as it makes it easier to return to standard down the road, and see what difference you get as the temperatures start to drop, when you get a cold day you'll see a massive difference - I definitely used to!

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Just a quick check mate, but you did reset the ECU after you'd fit the new filter?

Removing the precats shouldn't be too bad if it's like the IS I guess, but as for the main cat, removing that can be complicated as you'd probably need O2 simulators and stuff otherwise the car will keep throwing CEL's

There has also always been debate on the IS over whether the removal of precats actually does make any difference - some say yes, some say no, I never had mine done so can't honestly comment!

Removing the precats alone on my IS3 threw the CEL too !

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Removing the precats alone on my IS3 threw the CEL too !

Seeing as you boys both have the same engine I'd definitely be inclined to say leave the GS alone then for now, IMHO it's not been modified enough to require playing with the precats or cat yet, and will only complicate things come MOT time during the emissions test. As you can tell I like the easy life lol!

What did you do to resolve the CELs on your car then fella?

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Removing the precats will cause the AFM to run rich/lean at low/high rpm and therefore confuse the ECU. The only way to cure the problem is to remap.

The CEL can be cleared by the usual ECU reset.

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Well, just spoke with BBR http://www.bbrgti.com/home.php

these guys told me to throw the blitz away, put the factory box back in with a more efficient filter and to leave the cats alone. he said with my engine, the best way would be to remap it. he reckoned he could get 60bhp more out of the engine by playing around with the electronics..

should I believe him? he said to bring the car down and they will have a play for free..

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Well, just spoke with BBR http://www.bbrgti.com/home.php

these guys told me to throw the blitz away, put the factory box back in with a more efficient filter and to leave the cats alone. he said with my engine, the best way would be to remap it. he reckoned he could get 60bhp more out of the engine by playing around with the electronics..

should I believe him? he said to bring the car down and they will have a play for free..

60bhp just from tweeking the electronincs on a NA engine? :blink:

He's flying in a blue dream. Save your money!

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What did you do to resolve the CELs on your car then fella?

I had the 02 Sim installed by TDi, that solved the problem !

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I just spoke to Tony at Torque Developments in Enfield. Really friendly and honest dude, who reckons that after fitting the Blitz, my zaust cannot expel the gasses quickly enough.

Anyway, the car is going in Friday morning for the L-tuned zausts to be fitted on.. He did custom zausts for AJ too. He's gonna see what else he can do for my zaust to make it breathe easier..

Can't wait to zoom down to the ring!!! :D

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I just spoke to Tony at Torque Developments in Enfield.

Who? Where?

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I just spoke to Tony at Torque Developments in Enfield. Really friendly and honest dude, who reckons that after fitting the Blitz, my zaust cannot expel the gasses quickly enough.

Anyway, the car is going in Friday morning for the L-tuned zausts to be fitted on.. He did custom zausts for AJ too. He's gonna see what else he can do for my zaust to make it breathe easier..

Can't wait to zoom down to the ring!!! :D

These guys should be ok...i was quite pleased with mine! :D

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