[SVT5D]

My alternator finally gave up, killed by a bad battery at 210,000 miles. The rebuild shop had one of the clutched versions ready to go on the shelf, so I decided to give it a try. These were stock only on the SVTs built after 4/2004. The alternator itself is the same, the only difference is the switch from a 48mm solid pulley to a 60mm clutched pulley. That is a 25% reduction in alternator speed. Idle is smoother, but the most noticeable difference was a big reduction in rev hang that the SVT is known for.

Pros:
smoother and quieter idle
supposedly less stress on all serpentine components
25% underdrive should let the engine rev a little quicker
clutch lets the revs drop faster while the alternator freewheels

Cons:
cost $50 more
a longer belt is needed (I needed one anyway)
a possible failure point, although you can replace a clutch without removing the alternator from the car

 

[G-forces]

Cool! I would have paid that when I had my SVT. I never liked the hang in normal traffic, it took to long to rev-match for a smooth ride... only tolerable when speed shifting (with fresh shifter bushings, LOL).

 

[SVT5D]

Update if anyone is still here,
I have been getting a flicker on the battery warning light when the car sits at low idle for several minutes at a time. Voltage is at about 13.5, so its not a real problem just an annoyance. It seems to be happening less as time goes on, so maybe the computer is learning the new input voltage.