I'm not saying these are good ideas. But if they work they'd be cheap.
1) An electric exhaust valve cutout. I'm sure you can buy and electronic exhaust valve somewhere and install it in front of the cat preferrabley. That way you can switch from completely stock quiet exhaust to open headers for racing at the flick of a switch.

2) I believe that the stock ecu looks at air temperature and other sensor inputs to determine ign timing and also fuel enrichment. So the stock computer can modify the fuel ratio a little bit if you can change the inlet air temperature (I think) input. You could do this really easily and cheap with a potentiometer (spelling?) I get confused too easily to work out the specifics but if you could modify the sensor inputs perhaps you could adjust fuel ratio and timing advance/retard without an afc.

3) Really cheap dvd system. At one time you could buy a 5.6" lcd screen with dash mount stand for like $75 and an inverter for like $25 on ebay. For those of us that are lucky enough to have a ps2 already and a head unit that has aux inputs these are the only extra parts besides wires that we need. Mount the lcd on the dash and put the ps2 and inverter under the driver's seat (Because how many of us actually move our seat for passengers?) and run the audio inputs to the head unit and the video to the monitor and play away or watch dvd's. You can control the dvd portion of the ps2 with the controllers. It's in the book.

I'm putting my flame suit on for this one, they're just ideas I've been kicking around.

 

I just realized that there are 02 sensors to deal with for the exhaust cutout. Does anyone know where the 02 sensors are on a 97 gsr and whether or not the computer operates in closed or open loop when it's at wot?

 

On the end of the exhaust manifold and at the end of the catalyst. closed

 

sound good to me

 

the proof is in the pudding.

You have my vote