sry no it just means you have to put your old muffler on.or put a better 1 for more power

and for the engine wise. diffs on the engine like the traxxas 2.5 is like 109 on ebay. rebuild might cost 60-70 and cheap engines arent as powerful then the 2.5 soo depends pon whats engine you have and what engine your switching too

and sry for the mistake it was sapose to be long not low