Decat an N/A

hey guys, ive been thinking of decatting my N/A, its a J/spec 94, so.. does that mean the exhaust emissions for MOT? if so, cat is out of the question?

was also wondering on noise level difference? + power gains?

cheers,daz.

car will feel allot more responsive and have about a 10 to 20hp gain.

emissions are going to be way higher tough, MOT is out of the question when decatted it would have way to much Co2 comming from the exhaust to pass.

hmm will it be louder also? dont want it to noisy to be honest, does the 94 have to pass emmisions though? could always keep the cat in the shed for MOT's though.

hmm will it be louder also? dont want it to noisy to be honest, does the 94 have to pass emmisions though? could always keep the cat in the shed for MOT's though.

Pretty sure I've read about this somewhere in an MOT thread by someone. I'll see if I can find it.

Think the thread mentioned that the NA isn't on the MOT computer and so can't be failed on emissions???

Pretty sure I've read about this somewhere in an MOT thread by someone. I'll see if I can find it.

 

Think the thread mentioned that the NA isn't on the MOT computer and so can't be failed on emissions???

Found it...read the forth paragraph re NA's..just don't know if this has changed at all.

http://www.mkivsupra.net/vbb/showthread.php?214650-MOT-questions-and-queries-answered...&highlight=mot+questions

car will feel allot more responsive and have about a 10 to 20hp gain.

emissions are going to be way higher tough, MOT is out of the question when decatted it would have way to much Co2 comming from the exhaust to pass.

20hp from a decat on an N/A? Who told you that?

well cheers for the advice guys, MOt is coming up , might chuck one on after, as scott stated, 20bhp is alot from just a decat ?

hmm will it be louder also? dont want it to noisy to be honest, does the 94 have to pass emmisions though? could always keep the cat in the shed for MOT's though.

If you fit separate 1st and 2nd decat pipes it's a fairly easy job to refit the 2nd cat come MOT time. Saying that if everything is running as it should be ie. with working O2 sensors, cars have passed the emissions test with no cats fitted.

As said already said, removing the cats makes the car feel more responsive, it does make it quite a bit louder though, especially on an NA. If you're worried about it being to loud, you could just remove the 1st cat - the most restrictive - and leave the 2nd cat fitted.

20hp from a decat on an N/A? Who told you that?

Yeah you won't gain 20hp just removing the cats, 5-10hp maybe. An aftermarket exhaust, decats and tubular manifold may gain 10-20hp.

20hp from a decat on an N/A? Who told you that?

Expect 5hp at the most.

Yes it will be louder (Not sure which exhaust is the best to keep the noise down).

Emissions will be out, but I'd imagine the NA would be on the MOT Register? Got a friendly MOT centre you use?

Yes it will be louder (Not sure which exhaust is the best to keep the noise down).

Best to go for an exhaust designed specifically for the NA as they usually have narrower diameter pipework and additional silencer(s) on the mid pipe(s) eg. MT3280 Blitz NUR R or 770-25032 Fujitsubo Legalis R

cheers guys, well at the moment, i have a apexi megaphone dunk, from cat back, sounds awesome, i dont mind going abit louder, but not crazy, the middle section, im sure its like 3" maybe - 2 1/2" - back towards to the cat, exhaust exit is like 4 1/2". (115mm), so i would think it might be pretty noisy!

my friendly mot station always pulls another car up behind mine when it comes to testing the exhaust.ive no idea why but it passes every single time.

my friendly mot station always pulls another car up behind mine when it comes to testing the exhaust.ive no idea why but it passes every single time.

Last year my Supra had similar emissions results to a 1.4L fiesta. Go figure.

Last year my Supra had similar emissions results to a 1.4L fiesta. Go figure.

weard? good man

alright mate , i believe anything before 95 on imports is allowed without the cats in place , , however on an N/A it will be very tough to pass without the cats , turbos tend to have better emissions and should be even better with a EGR valve i think they have , or is that only uk spec ?? im not sure .

but de-catting a car is one of the best cheapest mod you can do and defo makes a differance that you will notice , you notice your RPM go up a lot shaper and more responsive and you will feel that little bit more power released .

ive always de-catted mycars , ive had 3 mr2 2 n/a and 1 turbo all where de-catted , i still passed my turbo through its m.o.t emissions even with the de-cat in place , but with n/a is next to impossible , anyhow you could always just keep your original exhaust in place and fit a de-cat and you will still notice the power and responsive feel , and will be not much louder than with the cats in place ,if you get a whole new exhaust system S/S and decat the lot , it will be very loud , and can set car alarms and house alarms off lol , but even so i love loud exhausts ,they sound fantastic !!

right about setting off car alarms lol, my NA had a tubby manifold with nur spec S backbox setting off car alarms >.>.

that was with the stock midpipe (catalytic converter) fitted , did love my sound so much tho

...however on an N/A it will be very tough to pass without the cats...

Nonsense. My 200,000 mile N/A has sailed through the emissions test every year (and not always at 'friendly' places either).

The emissions test must be really strict on Forza.

The emissions test must be really strict on Forza.

Nonsense. My 200,000 mile N/A has sailed through the emissions test every year (and not always at 'friendly' places either).

 

The emissions test must be really strict on Forza.

hi mate, is yours de-cat completely

Yep, full decat, stainless manifold & Whifbitz exhaust.

100% no problems at MOT time, not to loud etc..... does it feel more responsive? i still have the first cat fitted but want it out!

Why not just get an exhaust thats quiet like the whifbitz twin box, or one with a removeable silencer like the NUR spec R, mine is a NUR spec r, decatted with a SS OBX manifold and it is a hell of alot louder than any other NA i have heard.

100% no problems at MOT time, not to loud etc..... does it feel more responsive? i still have the first cat fitted but want it out!

Nonsense. My 200,000 mile N/A has sailed through the emissions test every year (and not always at 'friendly' places either).

That's what I was going to say... Mine has both decats, custom tubular manifold and custom exhaust and it was well within the limits of the NA decat emmisions test.

after reading all the comments i may have to decat my 94 n/a aswell