In my opinion, the carbon fiber driveshafts are well worth the money. I know $1K+ is hard to justify, but the results are amazing.
The advantages to carbon fiber over aluminum are the diameter, weight and strength. Generally aluminum driveshafts are quite a bit bigger and usually require modifications to the underside of the body to fit properly.
Why carbon fiber? (from PST's site)
- Lighter than steel or aluminum.
- Three times torsional strength of steel.
- Torsional spring rate allows better tire hook-up.
- Torsional spring rate allows smoother shifting.
- Less shock load to the differential.
- Eliminates or dampens high speed vibrations.
- Reduces transmission and differential breakage.
- A much greater safety factor - carbon fiber will return to a fiber and not create shrapnel under the car, as would aluminum or steel shafts.
-Zach