Dave, your Type T's are about 21.0 lbs each (which is lighter than most 17 inch wheels for M roadsters), while your stock wheels are going to be a few lbs heavier. The lighter weight wheel will help slightly for autocross situations. Reducing the unsprung weihgt is always a good thing, but I wouldn't think you will see major gains in your autocross times by doing so. I guess it depends on how competitive you are. If every tenth of a second counts................you get the idea. Hope that helps Aaron