Hi boyz and girlz. Im so excited. Im having my 1.8tdci remaped on thurs this week :)) got green cotton air fikter ordered. Now just thinking of making it decat and changing back box as exhaust pipe is quit big i wont bother making custom s/s exhaust for a min :) any thoughts? Thnx

Is it worth taking a cat out? Ive heard that they restrict power.

Sports cat is the better option these days or you'll have to be swapping the cat back in every time the MOT is due.

What abput just getting rid of inside and mig weld so its not noticeable? Lol i know its dodgy but ill pay less for that :)

Would depend what happened when it came to the emissions test at MOT time and if the remap disabled any lambda sensor faults that otherwise would bring the engine light on.

When we are talking about decats we have to be careful not to get mixed up with petrol and diesel engines -

Most diesel engines have a small, passive cat, there is no sensor, (no wires, no EML) the cat can be completely removed and the car can still easily pass the emmisions MOT test, as only particulates are measured on a diesel, diesel Ford owners have run decats for years, and passed several MOTs, no problem, recently the rules have tighened up, now there is to be a visual inspection, so it must look like there is a cat present, on many cars you cannot see if there is one or not, as there is an engine cover at the top, and an undertray on the bottom (the tester cannot remove covers) in this case as long as the (diesel) car can pass the particulates (smoke) test its ok - as carbon can build up on the surface of the cat, often a decat reduces smoke

On cars where the cat is visible it can be cut open and the innards removed - many Ford owners have done this and passed the MOT no problem (as above, it may even help reduce smoke, especially in conjunction with a solid EGR plate )

in tests, it was found the back- box was more restictive than the cat (diesel mk3 mondeo 2.0 &2.2, other turbo-diesels are similar)

On a petrol engined car its a different matter the presence of a cat may be detected by the emissions - and it may be diffucult to get the car running right and the emissions low enough to pass an MOT - in this case a high flow sports cat is probably the best way to go for a modern, petrol-engined road car

FOCA u r right as always :) thnx everyone for answers. I spoke yesterday with a man who knows the man who knows a tester man and ive.been told as long as they cant see it has been fiddled with im safe :) and yes its anly visual inspection

Guys :) i got smile from cheek to cheek :) just came back from garage where i got done my remap and ST intercooler map aswell on my 1.8tdci focus. It is just amazing. I used mobileECOtuning they are on fb. Its a rocket now not a car :)

I'll give up applying my limited knowledge to diesel's - they're way too confusing compared to good old petrol engines

If it spins wheel on 4th driving at 50mph it must be good :)

And yet u can get alot more from turbo diesel car than from some petrol :) im not talking about st or rs though lol