Dynojet Research Jet Kit - Stage 1 and 3 4111 Average horsepower increases of 15%-25%! Each DynoJet kit is precisely engineered to provide a simple and cost effective solution for all your riding needs Kit includes jets, needle, spring, shim and instructions Stage 1: stock engine/filters, stock/modified pipes; about a 5% power increase Stage 3: stock/mild modified engine, stock/modified pipes, individual air filters; drivability may be compromised, N/A for some motors; about a 10-15% power increase