i just purchased the fmf pipe my sons predator 90. i have not put in on yet but want to be prepared. i have already changed out the cdi box. we do most of our riding in the sand and live at sea level(obviously). if someone has put this pipe on their bike please let me know if i need to upgrade the clutch, rejet the carb or any this else needed. feel free to let me know where to get these parts also.
Polaris is hard to find upgrade parts.

 

polaris P90 is easy to find parts for, you will get prformance gains with a clutch, you also want to get a air filter and bigger main jet
hetrick racing or wrh racing can help you with the jets and filter if you don't already have a filter
you can find info here on the fmf pipe by doing a search

 

Goto WRHRACING.com

Great to deal with and upgrades are plentiful. As far as your FMF pipe, for what I understand you will need to do a clutch upgrade. Since you are doing the pipe you should also do an air filter upgrade. That will keep you from jetting twice. Get in touch with WRH they will point you in the right direction.

try miniatvs.com

much info and dealers on that site.