I used the heavy duty OME for a v8( designated for front) since I did a F>R swap. Well not exactly since mine is a l6 and initially the old saggy ones from the front to the back gave me about 2.5'' which was 0.5" lower than the front at the time. But got the OME HD like mentioned above and it sits now at 3.5", which is 0.5" higher that front, but that's ok since I do a lot of camping with wife and 3 kids-small and with the amount of gear( read as s**t) that i carry gets about 1'' lower. Have not experienced other after-market coils so won't be able to judge how others perform. So far so good.