We went to the GForce1320 Spool once we climbed about 800 rwhp. We were thinking the OEM LSD was probably getting near the end of its useful life. We went from the 3.91 gears in the prespool setup to standard 3.46 gears. Also at the same time we added GForce1320 stubs, hubs, CV shafts, the coil over kit, tubs, and modified lower control arms. The spool was a definite plus for biting on the street, espcially with the M6. After some hard driving though I began to stress other components in the OEM suspension. Eventually we went to the Ford Nine Inch IRS Setup to take advantage of the Wavetrac differential. Tight turns were playing havoc with the LCAs and trailing arms.