I've heard that they can cause problems too, I think it was from MinnFlyer. If it's just the extra length of them creating too much back pressure, maybe cutting them off just below the elbow bend would help the back-pessrue problem while still re-directing the oil. I have them on two Trainers, the NexStar, & the Tower. I haven't had any problems with them yet & they do work very well at lessening the amount of oil on my planes but I think just to be on the safe side I'll heed ELTIGRE's warning & cut the length off of them just beyond the elbow.