Only mod I know of is a K&N intake. I know its nothing impressive but still fun. The race went the way you would expect, I raped him. I didn't even count lengths because it was so bad. Even when we raced from around 60 with him having a full second head start I pulled on him hard, kinda surprised me.
YouTube - GTP VS Mustang GT Race 1
YouTube - GTP VS Mustang GT Race 2
YouTube - GTP VS Mustang GT Race 3