John Roberts

Hi there

Are there any ecu, electronic, emission or mechanical issues with fitting a center de-cat and rear box on a MY00 classic? I am only planning on removing the 2nd cat NOT the first (nearest the engine). Would i need one of those engine check detour boxes as per full de-cat or does everything stay the same as standard car? What kind of change, performance wise can I expect? Will it still pass the emissions test on the MOT?

Cheers all

Dannno

Take out both cats put to one side for mot time fit a full turbo back system, big difference with both power an noise.

Fuzz

no boxes or ecu fiddles required John.
With the standard downpipe cat still in place it should pass the MOT no problem, but if it doesn't it's a five minute job to put the centre one back in.

The biggest gain of power will come from changing the downpipe though if it's a power increase you are mainly after.

somewhere in the region of 5 bhp I'd expect with just a centre and back box

Andy

John Roberts

Cheers Andy and Danno

I dont want to go full de-cat....too much hassle for the bhp all I want is a more responsive toy for the weekend LOL ;-)

Thanks guys

Fuzz

will hardly be noticible John...

Best bang for buck is without doubt the downpipe.
Come MOT time all you need to fit will be the centre section CAT.

Andy

Jonty

Rather than power, will the flat-4 burble be richer/louder with the centre cat removed and straight-through back box..?

John, sorry... not wishing to hijack your thread... just thought I might be able to 'compliment' it.

Jonts.

Fuzz

depends on exhaust make as to what sound you get, everyone has a different opinion, but as a general rule yes.

Andy

Trap2Terrorist

iTrader: (3)

I've replaced my centre section to a decat pipe, plus a Magnex backbox (MY01 WRX). It passed its MOT within a week of having it changed, (I was a little worried I must admit but it wasn't necessary, it flew through the emissions test).

With these two changes plus a GREEN cotton panel filter I got an extra 7bhp from standard on my first rolling road test at Powerstation.

I've had it remapped now but before the remap it seemed a bit less responsive at low revs (<3k) but seemed to have more grunt at higher revs.

Hope this helps.

irisheric

last week i decated from the down pipe back i.e middle and box with a wrsprodrive backbox and magnatex strait through middle it sounds slightly louder
but soft, cant feel any difference in bhp will a remap help or total decat or induction

irisheric

sorry i ment to ask is a wrs prodrive backbox the same as my standard backbox as i was lead to believe the prodrive one was a better performance one



2001 classic

Dannno

replace the down pipe with a decat this is VERY restrictive and will give you a noticable difference in power, as for induction dont bother unless you are gone to go for a cold air jobbie like the APS and then you will probably need a remap

Dannno

If yo are looking for a real big power increase then a remap is the only way to go but you are talking a lot more expense.

Ben WRX Bug-Eye

Not meaning to hi-jack the thread...

Planning on a full-decat for my 2001 WRX at some point. Will it pass emissions come MOT time with just the OEM centre cat back on?

Dannno

keep both cats just in case m8

crispyduck

iTrader: (1)

John,

As others have said, if you have no other mods the decat center is fine without any further issues including MOT. You may be interested in my write up on this as I explain how a decat center effected my performance.

In summary, decat center = Scooby burple is back + very slightly better at high revs. IMHO not worth spending much money on unless going further - which would be decat downpipe :-)

-Steve

crispyduck

iTrader: (1)

Nope, might get away come MOT time by putting back on the center section CAT and getting it REALLY hot.
-Steve.

John Roberts

Thanks Guys

I only want to free the engine a little and get a little more growling to listen to!! I'm not going for big BHP......215 horses are enough for me at this point in time LOL!!
So I think it'll be a center de cat and back box for now....when I have the cash...although I feel that credit card trying to jump out of it's leather jacket!! LOL!!!!...
so you're sure that there aren't any sensors stuck to the classic MY00 center pipe?

As for hijacking the thread.......no worries guys the more info we all get out of the forums the easier it is for everyone to sort out their problems in the future

Thanks All
John

crispyduck

iTrader: (1)

Yes there IS a sensor on the center CAT. You can get a pipe with or without a hole for the 'old' sensor. If you disconnect your sensor, you'll need a CEL fix. If you leave it connected you may get away without a CEL fix.

If you need info on a CEL fix just let us know.

-Steve.

Jonty

Typical -- I've had a H&S de-cat pipe sat in my garage for months (just haven't gotten round to fitting it yet) and this is the first time I've heard about a centre section cat sensor. Doh!

Is the CEL fix public domain info..? Without looking I don't know if my H&S pipe has a hole for the sensor so I might need to use the CEL fix...

Cheers,

Jonts.

rigga

iTrader: (4)

just today replaced my center pipe and rear box on my my00 classic,bear in mind its a jap spec,so there was only a resonator in the center pipe and not a cat..... rear box is a miltek item,was orignally running an sti rear box off a p1,and the burble hardley existed... miltek silencer and standard center pipe was way better,very nice deep burble...now with the straight through center pipe added its a lot lot louder,can tootle along and not annoy the neighbours,but anything like on boost (2600 rpm) its LOUD..... if the main increase in noise happens when the downpipe cat is replaced i shall not bother..... that will be way too loud i would guess....for me anyways