I think there were some discussion on this in previous months. Do a seach for it and see what you find.I have a 97 burb with 5.7 vortec with 156000. I just put on K&N filter only. I did notice alittle more umph. and about a 2 MPG increase. But I wanted to know if a 6.5 or 6.2 could be a good option. any other suggestions?