Yo
the rb20 ecu gets a signal from the key when you hit 'start' which is basically the choke and definately helps with cold starts.
but apart from that there isn't any conventional choke like u'd find in a carby motor. if you find it hard to start in the morning, or after any long period of rest, you might wanna do a service on it, check plugs, fuel filter, etc..
also make sure your letting the fuel pump prime properly as fuel can drain back to the tank when sitting for a while, turning straight to start without sitting on IGN for a couple of seconds will turn the motor over before there is enough fuel pressure in the fuel rail.
chris.