How can I increase boost

[nos]

It seems like this has been asked before but I can't find a clear answer. I have a mountain kit MPI supercharger that was made for Yamaha Nytro's. The sled came with 28/28 pulleys which gives me around 6/7psi running at low elevation. I want to put a head gasket on and increase the boost so I can run on pump gas. What do I need to increase the boost to say 10psi? Is an intercooler necessary? Are the pulleys available somewhere online? MPI's site does not have them. Do I need a larger top or bottom to increase boost? I'm guessing bottom. Is there a chart that shows the relation of pulleys to boost out there? I'm hoping to get this done for less than $1k. For those who are running 10psi, is the sled easy enough to handle in tighter trails that are very common in upper WI? At first 6psi seemed a little overboard but I soon got used to that and wanted more. Maybe 10psi is not enough

 

[nos]

OK, so I should have read some of the recent posts. It looks like changing my upper pulley to 26 will increase my boost. Is that correct? Would it be safe to say the each tooth less will provide 2psi?

 

[full tilt viper]

25tx29b low elevation will be 9-10. Intercooler will help and extra fuel pump. Call mpi directly to pick up the pulleys.