meh... dont listen to tito. On my festiva, I had it mounted on the steering column shroud right in front of the speedometer. It wasn't the prettiest install, but it was one of the nicest tach setups I've used. I used a 5" sunpro tach. I recommend it. Very easy to read quickly, and the shift light was helpful.
Installation? Well... it took me about 2.5 hours or so, but I did a really nice job. I routed my own 14ga wire, all the connections were soldered and heatshinked, and I also routed all the wires through the dash and firewall myself. If you want to do a crappy job, you can probably do the whole install in about 30 minutes or so.