I have a 2006 z400 and i am doing some minor things to it to increase its performance and i saw the big gun rev box in motosport and was wondering if it is any good?? It says it lets you rev like 1200 more rpms and advances the timing some, if anybody knows if they are worth the $120 please let me know.

 

Spend another 60 bucks (check ebay)and get the Dynatek.
I would upgrade the valve springs first.