awtwac
When the belt is new, it's too tight. You'll want to stretch it a bit by hand and let it wear in on the car. I raced my 04R in stock during the winter on carpet to get familiar with how to set it up then some club racing and TCS on asphalt since the beginning of the year. I've probably got at least a dozen race days on the car and the front belt is still too tight for my liking. When you race stock or 540 (GT3) you want the belts as loose as you can get them without them jumping off the pullies so you don't waste your limited amount of power on drivetrain drag. It is TCS legal to run without the belt tensioner (in all classes) and you certainly won't need it for a while, so I suggest building it and sticking it in your pit box in case you need it later. With the mounting screws, the tensioner weighs 15 grams, so any amount of weight reduction you can get on an already overweight car is good! I would also make a transponder mount out of some scrap lexan rather than using the kit suppied mount. You can save a few more grams of weight there.