What are the advantages again of using a MAF vs. Speed Density, if any? My 2003 Trailblazer XL has a nice motor I wish could show up in a car, DOHC 4.2l Inline 6 with VVT, coated pistons, etc., and uses Speed Density. Don McKinnon 95 MTX - White/Mocha 92k miles Stage 1 Power Package with Stage 1cams Canyon Carver Road/Race Suspension Quaife & HiRevs Competition Clutch