I was pushing 9-11 lbs and my car wouldn't idle for crap...it would actually die when stopped if I didn't hold the gas. I guess it COULD have been other things, but I think others have had the same type of thing w/o a bypass. I'd just put one on so you're safe, however I also have read that w/ 6 lbs or under, a bypass isn't needed, so...I guess this post really didn't help much huh?