Here's a quiz for you DIY'ers

[kvc]

Originally Posted by Ven

I found this on realoem part X-reference for 17137639023, a 1.4 bar cap

RealOEM.com - Part Search

E53 (and e83 too in my case) fitment is applicable but no gasoline models. There may be no conspiracy but has this got anything to do with emissions and or regulations?

Thanks Ven. Already bit the bullet and awaiting its arrival. Will install the 1.4 bar cap hopefully next week. Funny, but the info I was provided with said it suited a swag of different models over many years, but not the E53. I don't think it has anything to do with emission - how would it make any difference to what's coming out of the tail pipes (engine still runs at the same temperature)?
I'll keep my original cap with me in the car, just in case, but I don't anticipate any problems.