I guy I know personally had they on his Em1 (now sold) and said they made a huge difference. This is the kid that can put in a set of axles in like 17 minutes, fabbes his own suspension parts and used to make weapons for the military so now I trust him. Just as a side note he has a mid 13 second early 80's volvo 242i sedan thats running 19lbs of boost. The point is is that he knows what he's talking about, plus I've heard lot of good things about them from various sources as well.