friends keep telling me that singles are better, b/c though less power... they are less likely to overheat

 

what you should do will depend on your goals for spool and max power (for whatever fuel you have available)

 

You need to speak to someone that knows what there talking about! There are way to many variables to just through out a quick answer. For example twins makeing 10 lbs of boost equals X single turbo at 10 lbs boost equals X. Whats the diffrence and why?

 

Totally wrong!! Singles make more power and less heat. How much more power is relative to amount of mods and boost. That is, if you're talking about stock twins, which I'm guessing you are by your post count.
Stock twins max out at a little under 400 horsepower and single turbos are for those wanting 400 and up. The catch is going to be the price, I and many others have put 15000+ dollars just into power mods. Just do some reading, it's all here on the forum.

 

stock twin turbo setup= stock or moderately modified
single turbo fd setup= high horsepower highly modified (many supporting mods required)