XSeries-forum

De cat is the way to go. Mine flys now and  sounds awesome.

Until you fail the MOT for not having them....

I'll not be decatting, but I'll get the inners knocked out. I'll eventually get them replaced but as emissions tests for MOTs are done whilst running LPG it'll not be an issue for that. I drive on petrol for 1% of my time in the vehicle... that's how I'll convince myself from an environment perspective

I'm not sure if this is related but on wife's Astra diesel had probs with cat -no DPF though and advise a fuel cleaner in this cas a diesel cleaner and to stay away from supermarket fuels as told vauxhall engines dont like it.

It could be the same for bm's if running on the cheaper fuels it may add to the clogging effect.

Since the cleaner has been in and we also ran the car for a constant 40 mins at 4000 Rpm to get it really hot,  in 3rd  about 65 up the motorway and back again, it certainly appears we have clear our cat. This the same method vauxhall say to do for the diesel cars with DPF's fitted to clear them.

I'm not sure if there is a petrol fuel cleaner but I guess there probably is one on the market.

Hth

BMW supply their own petrol and diesel cleaner additives now .... 

If it's a V8 check the condition of your PCV hoses..............replace if they are like bubble gum

That said mine wasn't misfiring when same were toast, (since replaced)