Had mine over a year now and no problems as of yet.
Clutch still doing fine, car was 3yrs old last week and 45000miles on it!
Running silly amounts of torque when activated and all is going well.
You want a wet kit, dry is very dangerous! It relies on the ecu adapting and adding extra fuel risking a high chance of detonation. Doubt an allready remapped car being able to cope on a dry kit! All wizards kits are wet and for that reason, they pride themselves on there safety record!
Wet kit has its own fuel feed and with the pulsoids correctly jetted it is jetted to give a perfect Fuel/Nitrous ratio.
25bhp will be okay, if you up it to 50bhp+ you really need a controller! You dont want to be firing in nitrous at too low an rpm, this is what the controller stops you doing. It has a build time and feeds it in gradually, much safer!