I was never a fan of my B4.2...hated it for quiet some time actually but the new 5 series Associated cars are really friggin good. My T5M is one the best RC's i've ever driven in 20 years. Associated has really stepped up their game with the high end offerings and in my opinion do it right as an upgrade options. Getting into a K car kit is a huge hit on the wallet right off the bat. Frankly 90% of the racers out there don't need or can feel the difference between the super high end goodies...including me.