Hiya, I've had it installed a couple of years now. No issues, just bolt on. Make sure you have the right kit for your year as I believe there are differences after 1980/81.
The only downside is more high frequency vibration. Vastly improved performance more than makes up for that
I had to back off the recommended ignition timing 2 degrees as I was getting pinging on a hot day under midrange load on 97RON 5%. I do have a non-standard Silent Hectik ignition. However, looking at the pitting on the 650 pistons, that had been going on before I got the bike!
Be prepared to replace things not in the kit. No1 being the exhaust retaining rings (the finned ones). If they have not been off very recently, dremel them part way through and cut them in half with a cold chisel. Don't try to undo them unless they move very easily. You may also find your exhaust system may not be as good as you thought. Consider lapping the valves in. Mine were sealing well and didn't need it. If you have any smoke on startup, rattles from the heads or other things that are not in good order, now is the time to fix them. Wear sunscreen.
Do not use silicon sealant anywhere near the long bolts. One of them is the oil feed to the rocker gear.
I think you get pushrod tube seals in the kit. You can silicon those, but I have not and no leaks. Use standard dino oil for a while. It won't bed in on synthetic. It will run very hot and your pipes will blue for the first few runs. Mine took at least 500 miles of taking it easy, and nearer 1000 to be completely happy. Short runs, keep the revs in the middle (3-4000), let it cool, run again. Heat and cooling cycles will bed it in most effectively. YMMV.
