Adding to the ongoing wish-list for my 2007 Si coupe, I came across a set of lightweight underdrive pulleys for it. Anything that reduces extra spinning mass is a winner in my book.
The manufacturer claims:
- Each set comes with a crank pulley and alternator pulley
- 4-8 hp gain (depending on application) plus torque gains across the entire RPM ranges
- Better throttle response
- Smoother engine operation (each pulley is engineered to exacting standards for weight distribution)
- Small underdrive (10 to 15%) on the crank pulley to further improve power output
- Accessories (like alternator) still maintain factory spec output