When you still have that much gap of a time difference, I strongly suggest getting more seat time and if you really want to get faster you will need some instruction or a friend to show you "faster" lines or where you are not on full throttle. For example at big willowsprings I was running 1:38-1:37 with stock setup, with rs3 and suspension upgrade I automatically dropped to 1:35 on the first lap. To be honest I wasn't going to upgrade anything until I ran 2 second faster but I got a great price on oil cooler, camber kit, used rs3 etc.....
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I am here:
http://maps.google.com/maps?ll=34.157855,-118.465439