hasnt been a new post here in a while so i figured id start one. had an underdrive pulley for my civic and noticed my engine was more responsive. currently have an udp on my 6cyl altima and noticed the difference. my xk has much more electronic bs than the two other cars and id prefer to keep the same diameter. would the weight from the iron pulley to the aluminum make that much of a difference? 2 to 3 lbs compared to 15 to 20. ive seen the kits for the other hemis, but not specifically the xk. new to the pushrod world so feel free to discuss the harmonic balancer issue also.