Bottom of the front end. The X2 was getting so much extra front end downforce, it was scraping against the concrete during hard braking.
I had great success using this clear lexan body at the ISC event at Rockingham. I hit 86 mph running the X2 front wheel drive before I blew a tire. I figured that If I can get some more downforce on the front end I could reach higher speeds before the tires blow. I cut a piece of lexan to extend over the front of the car by about an inch and the sides about an inch. This increased the front area and therefore increased the downforce. I was happy with the results. I hit 89 mph and the car felt nice and stable. I need considerably more run up room for the front wheel drive X2 than I do for the 4wd drive X5 and X3. The only problems I ran into was the bottom of the front end scraping the ground and wearing away the screws used for the motor mounts. For the next outing, I'm going to modify the suspension so the motor mount plate will stay level to the ground and not scrape the ground. I'm shooting for 100mph for the next testing session.