Screamin' Eagle Performance

They're built for slightly different buyers. SE is Harley's own performance arm: the Pro Street Tuner is engineered to the factory ECM and maintains the cleanest warranty position when dealer-fitted. V&H's FP4 is the aftermarket default — it auto-tunes across real riding conditions and the Eliminator slip-ons are the most-fitted Stage 1 pipe in the UK. In warranty and riding hard, lean SE; for the best value auto-tune and the classic V-twin bark, lean V&H.

For the bolt-on Stage 1 combination — intake, slip-ons, tune — it delivers a matched calibration that hits the right marks and keeps dealer warranty coverage. Going further with cams or displacement work is where you'll want the broader map depth of a Dynojet Power Vision or a full custom dyno session; the PST is optimised for the bolt-on range and excels there.

In practice, yes. The FP4 logs fuel-trim data during real riding and adjusts on the fly, which keeps rear-cylinder temperatures in a sensible range once the map has enough miles on it. It's not as tightly integrated as an SE calibration built around the factory ECM tables, but for a well-matched slip-on and intake combination it does the job without drama.