13 replies to this topic

[paynog]

What are your opinions on decat pipes do the sound good on the MPI'S or am i wasting my time?

[the.stroker]

They sound awesome,however you will have to replace the cat for the MOT every year,but if you can live with that then why not,is your car a daily drive,can be very noisy on the motorways and dual tracks.I did away with may CAT and went for a straight through stainless 75mm pipe from the lcb Y piece to a playmini center exit backbox

[Bungle]

you will be in trouble at a road side VOSA emissions test

[miniman retford]

I fitted a decat pipe & manflow single box system & it's passed the MOT emissions with no problem !

Edited by miniman retford, 25 January 2010 - 04:18 PM.

[R1minimagic]

Doesn't surprise me, the only reason they fit a cat is due to the emissions DF (deterioration factor).

[Sprocket]

Even a new engine will struggle to pass the 200ppm HC limit without a cat

[L400RAS]

They sound awesome

Agreed. I'm running standard manifold, decat pipe to a fletcher 1.75" side exit. Made a big difference (slightly louder), but MUCH deeper sound

[rick.spi]

my mini also passed without a cat

sounds throatier without 1!

[sirweste]

I'm very surprised any MPi passes without a CAT.

Is it worth fitting a decat pipe. No. Not in my opinion, it may sound nicer but you'll struggle to notice the difference in sounds when driving.
It just means you have one extra job to do come MOT time. Crawling around on the floor refitting the feckin thing with firegum burning your hands.

No its not worth it.

[Bean]

I've got the Maniflow LCB with lambda take-off - Allowing me to use my normal RC40-type exhaust!! Sounds GREAT!!

It is a little loud though, lol

Went straight through my emissions test, but then, mine's an 86 car with an MPi dropped in, so guess it's a little different?

[The_Mistro]

I've got the Maniflow LCB with lambda take-off - Allowing me to use my normal RC40-type exhaust!! Sounds GREAT!!

It is a little loud though, lol

Went straight through my emissions test, but then, mine's an 86 car with an MPi dropped in, so guess it's a little different?

yeah, they will do your emissions based on an 86 mini

[R1minimagic]

I'm very surprised any MPi passes without a CAT.

Is it worth fitting a decat pipe. No. Not in my opinion, it may sound nicer but you'll struggle to notice the difference in sounds when driving.
It just means you have one extra job to do come MOT time. Crawling around on the floor refitting the feckin thing with firegum burning your hands.

No its not worth it.

That depends whether you have a single or twin backbox after the cat. If it is a single you will definitely notice the difference in sound and either way it will rev a lot more freely above 4000rpm and higher into the rev range. It's definitely worth doing if you are prepared to spend half an hour changing it over (depends what time of year your MOT is I guess!). Just make sure you put plenty of copper grease on the studs and use new nuts each time. I used to do it every year on my lotus and even taking the undertray off I could do the whole job in about 15-20mins!

[sirweste]

it will rev a lot more freely above 4000rpm and higher into the rev range.

This surrpises me, as far as i was aware the cat is not a significant restriction.
Either way the MPi is getting over the torque +4K

[R1minimagic]

If you fit a decent low backpressure backbox to a car you can expect to get some hp gains and improvements so why does it surprise you that if you take the cat off (which is a lot more restrictive than a silencer) that you don't?!!

The catalyst will probably be giving something like 30-50mbar backpressure at the top end of the rev range which is a lot more than without a catalyst.

I have taken the cats off a few cars now (not just minis) and there is a very good improvement above about 4000rpm which is certainly worth having.