do they actually make a diff.?? and about how much of a diff should i expect???

Well do you like driving around sounding like a leafblower?...any way. Yes and no. They rob hp cuz the alternator is working harder to keep the charge that the electric blower are consuming. They choke the engine in high rpm(electic blowers ristricktive). They can brake into pieces or melt with engine heat. They'll give you a light boost in power in about idle to 2k rpm.

SO yes in about 4 hs of a fully chaged batt and good alternator . no after that.

Uhhhg....who am I kidding...THEY SUCK ....Just get that Vortech Suppercharger you've been looking at.

Complete and total waste of money. As TurboGTU said, they will start to come apart and fly into the engine under the heat most normal cars create. Also, they aren't metered, so imagine you take the vac line off the wastegate and run the turbo wide open. Instant lean condition, and bye bye motor.

use a hairdryer

I have a couple hairdryers....

1 t-25, 1 t-04, 1- ct-26, 2 or 3 t-II Chryslers, a few 16G's.... hehehe