I've had single stage kits on a number of EFI cars... always been fun to horse around with... was wondering on a Cayman S, if a Dry kit or Wet kit would work better. Looks to be about 75hp boost on a 3.4 liter engine. A wet kit is where you install a single fogger nozzle AFTER the throttle body directly into the air intake. Very often we thread the metal right where the rubber intake hose attaches to the intake manifold. It shoots a pre-measured shot of gas + NO2 in for some great power. Would make about 400hp for 10-15 seconds at a time...

But once you've used it for a while you learn to use it only when you need it. You might run thru 1st and 2nd with no juice and hit it right after shift to 3rd, again thru 4th... or more

 

In my opinion, if you want to just get some HP to horse around with, go with the wet kit. You won't run the risk of leaning out because of the way it works like you said. Also, i believe porsche stock plugs are beru copper plugs on most cars. Go 1 degree colder just to be on the safe side and then adjust as necessary.

As far as timing though, any adjustments tha should need to be made can probably be made by the Motronic unit itself.

NX and ZEX make some pretty comprehensive kits with throttle switches, etc etc.

I've hooked up go-juice to my 996 but havn't sprayed/tested it on a dyno yet.

I believe Alex from Sharkwerks (Sharky on this forum) has nitrous on his drag car. He can also chime in on this, as he's a good tuner and enthusiast.