hell man, you could always get a cryotech cooling system, you can get that purge look from co2 while still getting some useful benifits from it. believe me, while c02 is cheaper than n2o, it still costs to fill the bottle (anybody who has ever played paintball regularly can attest to this)
The Cryotech systems have a bottle about the size of a standard nitrous oxide bottle, only it's filled with co2, currently, they have three available options for the cryotech system.
the first is an Intake
cooler; it's a segment of aluminum tubing (like the kind on a conventional CAI
system) it has a bulb inside the tube, with fittings for co2 lines. when you engage the co2 control solenoid, it flash-freezes the bulb, dropping your Intake
air temps by about 25+ degrees.
the next option for the kit is a fuel cooler, it's a block that connects to your fuel rail, and it works in a similar manner as the Intake
cooler. it will chill the fuel going to the injectors for a denser fuel charge, and cool it off by about 35-40 degrees.
the final component is an intercooler ring, similar to the system many nitrous vendors make, it's a ring of tubing that attatches to the front of an intercooler to make your Intake
charge a lot colder, same premise, only it uses co2 rather than n2o. this bit is pretty much useless, unless you run a Turbo system.
all the coolers can be daisy chained into the line from the co2 bottle, you can add a nitrous purge solenoid at the end of the chain for your purge effect if you want, but you also get the benifits of additional cooling for your fuel and Intake
. may shave a little time off your 1/4 mile time, and it will definitely help prevent detonation if you use the fuel rail cooler.
I personally don't see the point, but hey, whatever floats your boat...