CT does good work, the problem with the Zillas and 250's is they have not updated, there porting and pipes with the evolution of the current technology for them. As for the 450's thats whats new so of course there up to date on that technology. There pipe design and port maps for quadracers are nearly 20 years old. The few builders that do a lot of zillas will extract quite a bit more usable power from the motor than CT will For about the same price.