GP1800R SVHO 350 Limited Edition, 2023 Yamaha

Quoted from RIVA Racing's page. Not measured here, and not reproducible without knowing the conditions, which are mostly not published.

Power

350 horsepower RIVA describes this as a reliable 350 horsepower. It does not say whether that is measured at the crank or the propshaft, on what fuel, or by whom.

Top speed

up to 86 mph RIVA's own wording is "top speeds up to 86mph", which is a ceiling rather than a result. Nobody here has measured it.

The most complete build in this archive, at twenty-two components, and the one that shows most clearly what a forced-induction four-stroke build costs in parts count: ten of the twenty-two are engine items, and three of those exist only to keep the supercharged motor alive rather than to make it faster. The supercharger shaft, the valve retainers and the cooling upgrade are reliability parts. Two components carry no part number because RIVA lists none for them, and they are recorded as null rather than guessed.

Whether any of it is legal in your class. A builder describing its own product, including by a class name, is not a check against a rulebook. Class legality holds the checks that name a section and a person.

Whether it would do the same on your machine. A quoted top speed is one builder's result on one craft, usually without the conditions, the rider weight or the fuel.