Just recently bought a 98 powderspecial 600 efi. I believe it has already been piped by the way that it sounds, I was wondering what would be the best thing to do to the engine to get a little more power. also it was sitting for two years before I bought it and it bogs down in the lower end. I believe that the injectors are just dirty and need to be cleaned.

If it sat for 2 years, you should clean out the throttle body, just to be sure there's wax or gummed fuel in it, but your low end bog could be clutching and or belt problems too.

I will clean the throttle body, I doubt that it is the belt just from the way the the sled is reacting. thanks for you reply though

It shouldn't be to hard to tell if it is piped or maybe it just has an aftermarket silencer on it. If it just has the silencer then it probably isn't any more powerful then it was stock. With it being EFI you wont get the full gain out of it, but I believe for that year D&D made an replacement EFI chip that increased power. Gut the airbox and a good clutch setup should give you some extra ponnies.