I installed one yesterday. Seems like snake oil to me. Other than looking nicer and better build quality, it doesn't seem any different than the stock tensioner. The spring rate "feels" the same as the stocker. I ordered it from BPS, and it came with a 63mm pulley. It's smaller than stock, but the unit as a whole weighs exactly the same according to my scale.
Save your money. I haven't driven the car with it yet, though. Maybe my opinion will change after a hard drive, but I'm not betting on it.
Save your money. I haven't driven the car with it yet, though. Maybe my opinion will change after a hard drive, but I'm not betting on it.