I've had good results in economy and a noticeable "pep" increase with the K&N filter in our three Isuzu 3.5 vehicles (two VX). With the PV2 and Morgan-tec on the Dragon there was a big change per the butt-dyno. Just remember that for an intake mod to work well you need to couple it with an exhaust mod. What you're really doing is helping the engine breathe easier. You're not going to get radical gains, but noticeable ones worth the relatively small investment. After that it's induction and porting.