Running a decat

[Weston]

Whats the difference between a large bore downpipe and decat?

A large bore down pipe will be wider than standard, 3" v. 2.75" I believe. A decat means the cat material from within the DP has been removed so essentially it's just an empty pipe. Both allow greater flow through the exhaust.

[pd9264]

i put a decat on my gti and my eml hasnt come on, iv done about 500 miles. also iv got an extension piece on my second lamda sensor. its got a little hole in the bottom where it enters the exhaust. it stops the sensor picking up too much exhaust gas so it doesnt relise its got a decat. its only a cheap toyosport decat though.

[nezquick]

Just a quick question, I have a decat downpipe (3") mated to a resonated milly, the check light came on but cleared with vagcom - I am expecting it to come back within the 100 miles again. Is this potentially a MOT failure recipe? I love the sound of mine, really nice and quite when you want it to be and then when you give it some boot it sounds   

[Tamiyoman]

No CAT= MOT FAIL, light on or otherwise 

[nezquick]

  thought as much, thats alright I have a friend in the business so im sure he can help 

[Tamiyoman]

thought as much, thats alright I have a friend in the business so im sure he can help 

Like most folks on here just stick it back on for the day, get MOT done then take off afterwards, only trouble is you will face fines etc if pulled over by the Highway Wombles (They operate regularly on A17).

[nezquick]

Yeah I think Ill do that although he passed me last time with a previous car that maybe shouldn't of passed. hmm, my car is quite enough not to draw attention to it if im gentle on the pedal so hopefully shouldn't have much of a problem thats why im tempted to just weld in a highflow sports cat but christ they're expensive

[Tamiyoman]

Yeah I think Ill do that although he passed me last time with a previous car that maybe shouldn't of passed. hmm, my car is quite enough not to draw attention to it if im gentle on the pedal so hopefully shouldn't have much of a problem thats why im tempted to just weld in a highflow sports cat but christ they're expensive

I have been pulled over by the highway wombles 5 times in 6 years always on A17 (At least they are not shutting the road!!), when you pull in its usually wagons, Vans, HGV's (Checking weights, dipping tanks etc as lots of Pikeys round Cambridgeshire/Lincolnshire using red diseasal) and Sports cars (clearly looking for Cat removals, tyres etc), had the pipe up my cars exhaust every time, they actually tried to stop me another time and started waving me in, just drove past them as I was in a bit of a hurry and no time for them messing about!!