Throttle Body spacer question

I'm looking for better gas mileage and HP for my 1991 s-10 Blazer V6 4.3L TBI engine, and have heard some things about throttle body spacers.
The AirAid throttle body spacer promises to increase both horsepower and gas mileage for about $75.

Has anyone used a TBS, and are they as effective as they claim? Are they worth the $75 for thier benefits? Or is it just a gimick?

I was also considering a K&N factory filter replacement (just a direct replacement, not an intake) are these worth anything? Are they effective?

Thanks for any advice you can provide,
-FRS2004

on the adding of length to the intake.
Very good to lower the RPM that provides maximum torque point.
Very bad because it does this by lowering the HP maximum.

If it has swirl porting, rougness with a pattern, it can help to get a better combustion. Not the tornado claimed amount but improved burn.

http://members.roadfly.com/kcroncarter/tornado.GIF

Real deal is it may feel more powerful because the torque is at a lower RPM. Any mileage improvement will be in the statistical and not measureable amount.

A change of differential ratio is a better value.

Later,