[whosdat]

would anyone know of any aftermarket "bolt-on" items that would increase my mileage in my 2000 trailblazer and 98 astrovan?
both with the 4.3 vortex motors.
i was thinking in regards to the air filter

[redeye-racing]

k&n air filter, hi-flow cat-back exhaust, hi-flow cats,power programers or chips, upper intake spacers,most of all stay ontop of tune ups and servicing. i've found that almost anything that makes more horsepower[ within reason] can inprove your fuel mileage. Have you ever heard of a Motorvac machine? HUGE fuel savings...goto-www.motorvac.com for more info. one tech i know offered your money back if you didn't find big fuel savings. he never had to give back one red cent.

[Spacemonkey6401]

Exactly what does teh motorvac machine do? I went to the sight and didn't see what it did.

[Henry]

All add-ons usually minimize the system performance. The system on its own gives a mileage which is only true.

[young]

No its not like that. Not all add ons decreases the performance for example engine boosters increases the speed.