So i ran my first AX Today and within 4 runs dropped my time over 4 seconds. I was running NS(Novice Street) class and come in 4th out of 15(To heavily modified M3 and S2000, and then close behind RSX Type S. So im pretty happy about that, the guy in the Type S had ran 3 or 4 events before and beat me by 3 tenths. On my fastest Run I ran 45.4 compared to a porsche 911 at 44.8 and another at 45.5. YESSSS... I felt though i was held up a lot with the lack of LSD(keep in mind i still have a lot of room for improvement in driving skill) Now if i have a cat delete and 4-1 headers automatically im Street Prepared right? So DSP? Whereas with shorties and cat in Street touring? If this is so im considering an LSD because its allowed in Prepared. But if i can retain touring what does this mean-"Limited Slip Differentials
STC, STS, STF – No limited slip differentials are permitted except for factory standard viscous coupler type units.
STX, STU, STR – Only standard (as defined in Section 12.4) limited slip differentials (LSD) are allowed on AWD vehicles. For AWD vehicles that did not come with any type of limited slip differential (including center differential or transfer case), a single aftermarket LSD may be added. 2WD vehicles may use any LSD unit." Can someone Explain what these STC,STS/STX ect mean and where my focus would fall? Am i allowed to use LSD in touring since theres a factory option?