from experience using p90s, its always better to install mosfets early on when using this system.p90 trigger wire sets tend to be rare ( at least here in our place ).if you have the extra funds,its always a good idea to buy a compatible p90 trigger wireset or assembly.it will fix your single or full auto problems.if you want a quick fix,i saw a diy before.when the p90 gbox is removed you will see a thick wire inside the receiver box.thats the part that engages the trigger to the gbox.the end where the gox trigger and the thick wire meets has a spacer placed in between it.the sample that i saw, the wire to gbox trigger contact has at least 4 rolls of electric wire serving as a spacer to make the engagement more responsive.hope this helps
