I understand the rules in the US are "run what you brung".
Here in Europe we do it a bit differently. Our classes are open only to certain cars and all parts and hop-ups must be from Tamiya and for the model specified. Even with rules like these (easy teching) there are still people that try to bend the rules. Thats why more than half the Swiss team this year was disqwalified
As if the tech guys (who did a good job!) wouldn't see twisted armatures and illegaly timed stock motors
