if they do . i haven't noticed to be honest mate , they take a bit to get the spring setting correct but all that I've really noticed is the sound and not performance. they only make the sound when you release the throttle at higher revs, so round town they are fairly silent.Does it really help in terms of performances?
Not too sure mate . Seems odd a bov would cause that. Where did you have the spring set?Interesting. I also have had these for about 18 Months and since iv fitted them iv had a problem with using engine oil. Spoke to a lot of people about it and most have said it cant be because of the BOV's. It seems to coincidental so iv turned them off for the last 6 weeks & surprise surprise it seems to have stopped using oil !
Maybe its because iv got the spring too tight or something. It would be good to see if anyone else has the same issue.