Finally had a nice solid run with the B4.1 extended chassis, I really struggled with it the first time out, so bad I was close to throwing the towel in. Anyways I was using cavs worlds set but I had installed Kyosho big bores with yellow springs in the rear and pink in front. Starting the day out the car was not bad but I decided to throw the v2s (std cav setup)green rear/brown front back on to see how it felt and it was much much better! I really think its a matter of finding out the right springs for the big bores and they should be good as well. Ended up taking TQ, led some of the main, came home second, car was real nice and stable.