Is it possible to do nitrous control by gear , so first doesnt get sprayed at all then the controller works for the rest of the gears?

 

I'm pretty sure. Nitrous Express makes the Maximizer 4 which I was looking at the other day. Pretty slick device

 

The NOS Launcher is capable of doing a first gear lockout if you can find one. Also, if you want something that's more capable the Lingenfelter NCC-002 is capable of controlling the nitrous by gear. The NCC is widely recognized as being one of the most capable controllers out on the market right now, and has lots of options. The Launcher will set you back about $440 if you can find one new, and right now they are pretty scarce because Holley hasn't built anymore. A NCC-002 starts at $649.99 for the 'basic' version without the wiring harness, and the NCC-002 with the wiring harness, fuel and nitrous pressure sensors, and EFI apps is $874.95

 

you could put a micro switch on the shifter that disables the nitrous when the trans is in first gear. like a throttle switch but in the normally closed position so when the switch is depressed by the shifter it removes the signal to the nitrous system. that would be way cheaper then any of the controls mentioned before.

 

Find and old microedge. It worked great for me.