I have a Puck in my rig. I'd ask how old the unit is as well as how many miles are on the unit. I paid a little over $600 (I think it was something like $620) when I bought mine 6 months ago. The dealer advertisement has said power increases of 65hp & 200#'s torque. Secondly, the unit can be custom tuned by purchasing a package from the manufacturer. Basically you buy this package and it comes with the hardware and software for you computer to make your own custom power tunes. I've tried to contact DiabloSport a few times thru their website to get confirmation of this, as well as to ask about features of the unit that I'd like clarification on i. e. if there's an integrated boost fooler, whether the unit adds fuel only, advances the timing, or both, etc. So far my unit has been flawless in operation and power is very smooth. I would like to see better customer support from the manufacturer though.
If the miles are low and the unit is relatively new, I'd say go for it.
Brian [><]