Wire splice and holes are free, and buying a few jets to suit your setup won't cost much either. Best advice though is to spend some money at a dyno and have the bike setup by a pro. It will save you lots of money in the long run.

Changing the cans will have some small effect, but the MC21 pipes flow pretty well already.

With all three of those mods, and with conservative road jetting you should see upwards of 58hp. As you tune the bike higher and start making low to mid sixties you'll find the jetting becomes more critical, and the chances of siezure increase massively. And a sieze will cost you roughly £160 depending how bad it is.
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MC21SP Plaything
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Triumph 9551 Daytona Big boys toy
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