ImprezedRS sells (or used to and may again, I dunno) a small kit for switching the location of the speedometer and tachometer on 98-01 RS. I haven't seen any kind of review of the install so I figured I'd write up my experience and impression.
All you are really getting for your money is a new insert you put into the gauge cluster that switches the location of the speedo and tach. Then you need to cut the existing traces and solder some wires so the right signals go to the right needles.
The install was relatively straightforward. You need to undo two screws at the top of the gauge trim. Make sure you lower your steering wheel as much as possible. There are two tabs at the bottom holding it in so you need to pull fairly hard to get those to pop out. It also helps to lower the steering wheel as much as possible. After you get the trim out, there are three screws holding in the gauge cluster itself. Then there are three wire harnesses you'll need to unplug. Then you can take the whole thing out of your car and go inside where it is warm.
Pulling the cluster apart is pretty easy. You need to be careful that you pull straight up on the needles when you remove them so that you don't break the thin metal thing that attaches them to the cluster. You may need to pull hard to get them out but as long as you are pulling straight up you should be okay. There is also a little plastic lock thingie at the base of the needle that you'll need to pop out because the gauge face can be removed. You'll also want to take out the trip odometer reset button to make it easier to do the soldering later. There is a little tab you need to press in to get the assembly to pop out.
The instructions ImprezedRS has show what traces you need to cut. Basically there are 8. The tach and speedo are driven by four signals a piece. COS+, COS-, SIN+, and SIN-. If you look on the back you can see the traces are labelled. I cut the 8 traces using an x-acto knife. I used a multimeter to check that I had actually completely severed the connection. ImprezedRS sent along some wire that I soldered into place. There is a slight typo in his instructions but it should be easy enough to spot. You are just rerouting the 4 different signals from one side of the cluster to the other side (since you are switching the places of the tach and speedo). So the place that used to receive COS+ needs to have a wire connecting it to the other COS+. When you actually look at the PCB it'll all make sense.
Then just put everything back together and put it in your car. Recalibration isn't hard but it is a little tedious. I had trouble getting the needles just right. And then when I did get them just right, they'd be pressed in too far so they'd stick a little bit. So I'd have to pull them out and try again. It only took maybe 5 or 10 minutes to get everything recalibrated, though.
When you look at the gauge faces up close they definitely look hand made. The cuts aren't quite as machine crisp and clean as the OEM ones. At first I was a little concerned about this but once you get the gauge cluster back in place you'll find it isn't an issue...when you aren't looking at the gauge face from 6 inches away you can't see the slight irregularities.
This mod also changed the color of the gauges to blue. I like it, even though it doesn't match everything else anymore (like the clock, the radio, heating controls, etc). Other people might prefer to retain a more stock look.
My only real complaint is with the lighted indicators (i.e. door open, running out of gas, seat belts not fastened, etc). They aren't as nicely done as the OEM ones. Looking at how the OEM gauge face is constructed I can see why, it would certainly require more work to make that happen. If you look at the pictures ImprezedRS has posted you can see what I'm talking about. With the OEM gauge face you can't really see the indicators at all unless the light behind them lights up. With the new kit you can see them even when the light is off. They also aren't colored like the OEM ones are.
Overall I like the mod. It doesn't make my car go faster or anything but I had fun taking my car apart and learning how to solder and stuff. It was relatively easy as long as you have access to a soldering iron, I'm no car god and I was able to do it in an hour or so. Like I said, my only real complaint is with those status indicators. Maybe some day I'll be really enterprising and make my own gauge face to fix that problem.
Here are some URLs to the original posts about this.