My car is 3300 lbs with me in it. 5.9 magnum with a 4" crank making 406" hyd roller (limited lift with factory lifters) motor, 904 basicly stock with TA vb with 4.10 rear gear with 29" tires. I had a BTE 9.5" converter handing out a 1.58 60 ft time with a 11.50's 1/4 et in good air and 11.70's in heat. Changed to a TA 8" verter and car went (good air) 1.44 60 ft with an et of 10.92 at 122 mph, (heat / bad track prep) 1.49 / 1.50 60 ft, 11.03 1/4 mile at 119 mph. A good converter will make you think you are in someone elses car, haha. Old verter stalled around 3300 flashing at 4000 or so. 8" is stalling 4200 or so with a flash around 4900 rpm. Buy a good one and you are done with that area. If you buy 2 or 3 cheap ones, you could have had 1 good one and didn't have to pull trans many times. talk to the RB guys and find what is working with your numbers.