(I'm a bit late reading this post just now ) when increasing the bhp's stronger clutchsprings are highly recommanded. For me, I should install stronger valvesprings only when you are also increasing rpm.over 7200rpm.However, when your bike is Sc/turbo and 'cruising'round 7000 rpm, because of boostpressure, stronger ones are recommanded.For me, an issue could be the faster wear of camchain and blades when installing stronger valvesprings.Not to mention other wear...
On the bit 'optimistic' TTS 'dyno' my roadster was spitting out about 390 bhp, about same torque, rearwheel, at 21.75 psi Sc boost at 6800rpm.I got already Lush valvesprings but now I am doubting installing those because of the mentioned wear…