I have a 4-speed. From what I've heard, I'm glad I do. I have to ask though, if you don't want to spend $150 on a SGII, why do you want to try the idea of swapping trannies? Don't get me wrong, I think it would definitely be worth it, but the initial cost is still going to be a major setback, just like the SG, and probably worse. If you can find a JY tranny then great, but don't forget you'll need at the very least the ECM along with any other doodads to go with the mod. Also, would you install it yourself (that would help with cost, obviously)?
I would say if you want to do mechanical mods to make your '97 more fuel efficient, then go for it, but people here like changing the driver before the car, so don't expect them to tell you something different. If you can find a JY later model Corolla to be a donor car then great. Use the tranny, ECM, MAF sensor (instead of the MAP), etc. I forget does the '97 have VVT-i? Actually I think you have an AFE engine, so probably not. You could always find a newer 8th gen engine, tranny and whatever else. That would give you a nice efficient car with all the "modern" equipment. Again, though... cost. It just depends on how far down that road you want to go.
I also didn't want to put down 2 bills for a device, so I got the Ultragauge. I'm glad I did. The UG can have up to 8 gauges at once and multiple pages which you "turn" with the push of a button. I found this to be better, because I like having them all on one screen and not have to pre-decide what gauges will be useful that day. The best part is that it was half the price of the SG! You might want to look into that instead.
Don't forget, you can do cheap aero mods to improve economy. Grab some inexpensive lawn edging and make an air dam and see what that does for you. Cloropast the belly, just stay away from the exhaust. There are a number of things you can use for a grill block (lawn edging and cloroplast included). If your comfortable, you can remove the passenger mirror. A $150 can go a long way with these mods and an ultragauge. Depending on how much you drive you could see the $150 back in your pocket with these mods in a matter of months and you don't have to do any major testing, it's been proven by people here many times over.
Hope this helps and good luck!
