2 & 1/2 or 3" downpipe

[martybelfastt5]

called into a local exhaust centre,, powerflow speacilists full 2 1/2 system from turbo back 400 ...and he reckons a 3" downpipe wont make any difference also reckons i dont need a high flow cat just do without he has same on his 02 v70 t5 three years and never failed an mot says with my cars age its no an essential part lol, what the thoughts on this here?

[Volvostorm]

He needs to update himself, the MOT rules change on 1st January, all cars that were oridginally fitted with a cat, will need one, regardless if it passes the emissions or not.

[The Flying Moose]

He needs to update himself, the MOT rules change on 1st January, all cars that were oridginally fitted with a cat, will need one, regardless if it passes the emissions or not.

Easy solution... cut a standard Volvo cat in half, gut it and weld it back together again, they will never know! Thats my plan at least.

The reason behind this I believe is that they will be taking a picture of the cat at MOT time.

[smithson007]

Any kind of cat ie. sports cat or does it have to be the original?

[Volvostorm]

Any kind of cat ie. sports cat or does it have to be the original?

As far as I know, any cat will do.

[Alan M]

A true full 3" system will always be a better way to go also if well built.

[martybelfastt5]

so just having a 3" downpipe isnt nessacary if the rest of the system is 2&1/2?

[The Flying Moose]

I think there are many pro's and con's.

Personally I wouldnt fit a 3" downpipe and would stick with a 2.5". By fitting the larger downpipe you will reduce back pressure and lower the torque output of the car.

I know too its difficult to make a full 3" system for these as in most cases the pipework needs to be reduced to 2.5 over the rear axle.

Personally I would have a 2.5 system from turbo to back, therefore no pressure changes and not too loud. A 3" system turbo back will drone.

[AndysR]

Go 3" you know you want to! They don't drone that badly ;)

[Yosser]

He needs to update himself, the MOT rules change on 1st January, all cars that were oridginally fitted with a cat, will need one, regardless if it passes the emissions or not.

Source please?

[JelT5]

Well, when my car is actually running (not at the mo lol) I have a standard decat d/p coupled to a JT 3" single box and it is really f**king deafening inside and out, spits fire and pops and bangs like a TVR.

I love it, you can never make enough noise, what's this droning stuff anyway Emlyn ;)

[Volvostorm]

Source please?

Ive borrowed this off another forum, but I know its true, a mate of mine is a qualified tester, and he has just been on the seminar.

Its not as bad as it looks though:

http://vauxhall-sri.co.uk/showthread.php?t=4002

[LiamT4]

2.5" better torque low down, 3" more higher up the revs?

[Yosser]

Ive borrowed this off another forum, but I know its true, a mate of mine is a qualified tester, and he has just been on the seminar.

Its not as bad as it looks though:

http://vauxhall-sri.co.uk/showthread.php?t=4002

Thanks.

Found the new MOT manual online now: http://www.dft.gov.uk/vosa/repository/MOT%20Inspection%20Manual.pdf

[p fandango]

3" more higher up the revs?
especially once the turbo kicks in