I think i might decat the VRS, is it straight off the turbo or down from the turbo.

Whats the cheapest route or does it need to be custom? I do not want an aftermarket exhaust.

Is it likely to give a small power increase or is it a high flow CAT?

A small power increase would be nice.

Can anyone elobrate on all the differences the decat has given, e.g sound,spol etc etc

Its under the car, cheapest way is cut it off and sleeve abit of pipe in its place.

I love the sound of mine now it has a decat!

Cool so chop it out and weld a pipe in place? same diameter?

What sort of noise does it make?

Is it okay for an MOT? thought it wasnt a requirement?

Anyone know if it eeks a little more power or not?

I'd like to know more too. On the MOT side of things I believe it can be failed (as of a certain date) if the cat is not present? In response to this I've noticed that people just remove the cat, smash all the interior out with a broom handle and refit it hollow, then have the CEL mapped out?

You could do that, however a little known fact (i tuned petrol cars as a hobby done about 13 cars on standalones/piggybacks) some hollow cat which have had the guts took out cause bad resonances which alter exhaust pulse width because you have step even if its tapers (imagine plates stacked together in line if the get out of line or moved a lot and don't follow it can effect performance not sure if this would apply to this car or a diesel), so for me i would have a pipe same diameter all the way through.

I have seen on vtec engines when lowering vtec this sort of mod when just smashing out the guts cause a slight power drop/resonance - as i say might be not the case on diesels/this car.

Not sure if it would bring a CEL up unless it had some sort of sensor in the pipe that would then read erroneous readings because of the air flow and the position of the sensor.

Not sure on the MOT side.

I had a decat miltek on my 06 (BLT) and thought it improved performance slightly, certainly sounded better.

Understand what your saying about the altered pulse and agree. Exhaust tuning is more than just a pipe lol.

However as we have a turbo, doesn't this cancel out the pulses so doesn't have the effect like a NA.

You could do that, however a little known fact (i tuned petrol cars as a hobby done about 13 cars on standalones/piggybacks) some hollow cat which have had the guts took out cause bad resonances which alter exhaust pulse width because you have step even if its tapers (imagine plates stacked together in line if the get out of line or moved a lot and don't follow it can effect performance not sure if this would apply to this car or a diesel), so for me i would have a pipe same diameter all the way through.

I have seen on vtec engines when lowering vtec this sort of mod when just smashing out the guts cause a slight power drop/resonance - as i say might be not the case on diesels/this car.

Not sure if it would bring a CEL up unless it had some sort of sensor in the pipe that would then read erroneous readings because of the air flow and the position of the sensor.

Not sure on the MOT side.

sorry to go off topic a little but every 4 stroke motorcycle i have owned has had a bulge in the exhaust at the bottom of the downpipes. why would they do this if it decreases power? Although i do agree that an exhaust does need to be tuned to the engine

Edited 9 March, 201313 yr by Holmesie

I believe this buldge alters the pulses in a good way.

http://en.m.wikipedia.org/wiki/Expansion_chamber#section_1

This is 2 stroke. Not sure effects on 4 stroke.

http://en.m.wikipedi...amber#section_1

This is 2 stroke. Not sure effects on 4 stroke.

http://www.crfsonly....roducts_id/3129

thats an example of a 4 stoke 450cc exhaust with the buldge in

http://www.ebay.co.uk/itm/CB600F-CB-600-CB600-HORNET-EXHAUST-DOWN-PIPES-98-02-NEW-STAINLESS-STEEL-/130864794464?pt=UK_Motorcycle_Parts&hash=item1e78264b60

thats a standard honda exhaust off my current bike 2 bulges jus after it goes from 4 to 2

Edited 9 March, 201313 yr by Holmesie

Because the buldge increases surface area for the honey comb of the cat to help with emissions etc and help negate performance reductions caused by this, remove the the cat contents keep the buldge and this has a negative effect. In a away in standard form a cat contents present with a buldge helps performance so fabooka is right.

I own a Honda too, every decat pipe you buy is the same diameter so no buldge.

You can get decat pipes that have a slight buldge but not contents with a metal sheet with holes in to help resonance primarily for drone though.

Edited 9 March, 201313 yr by ajs_vrs

mines a s reg - 99 plate so no cat .... and such as the crf has no cat and early ones had the bulge too and are loud as **** ..... it always gets mentioned as a power bulge on websites

your right theres a pic in there of the inside of a powerbomb exhaust

http://www.thumpertalk.com/topic/527516-inside-view-of-a-fmf-powerbombmegabomb-fab-your-own/

passed my mot with no cat and boxes.

The place where I get my cars MOT'd also said that no cat is required - just a smoke test.

A decat may help the turbo spool up quicker so will need mapping to suit ideally

Thor motorsport did an rr comparison on a leon 150 tdi

They kept standard cat but got rid of the backbox and replaced it with a staright through pipe

Back to back rr's showed on a standard car an increase of 5bhp and 9lb/ft of torque

Interesting, I wouldn't have thought the back box would be holding back any real measurable power, I always thought it'd be the cat.