Estimates based upon what I've done, watched others do, and watching multiple Rocks in various configs doing many dyno runs.
Fullbox to empty catbox= 2-3 RWHP.
Fullbox to empty cat-bypass= 3-4 RWHP
Empty box to cat bypass= 2 RWHP
3Factory Pipes to 3Off-Road= 2-3 RWHP
Going from a full cat stock pipes to cat bypass and off roads will net 5-7 RWHP with appropriate Triumph tune.
Jardines with a fueler will net 10-12 RWHP
Triple K&N's will add 6-10 RWHP, depending on configuration of exhaust.
Remeber, 5 RWHP on a bike contitutes a solid increase in power, usually measurable by SOTP.
3KN/Jars/competent DynoTune is good for roughly +20/15 RWHP/TQ
Doing what TT did will net a lot of free power, and greatly reduce weight.
Very shortly I'm going to a single Jardine, to reduce another 9 lbs., which may also be good for +1-2 RWHP