I see. OK, I think I may have to go your route, except that I didn't buy the mazdatrix t-stat elbow. I have the crappy FG plastic one and the S4 unit is a different bolt pattern.

Yeah, mine is an S5 elbow as well, nevermind the fact that I just got a new one from Atkins too! It ran me $66.00!

Drilling and tapping a new sensor in the WP housing near the factory sensor is the best place. I have a new gauge, but have not torn the housing off, because I don't see a point, until there is a problem that is. The stock gauge sucks ass, but I can judge it pretty well. I already have an aftermarket gauge in the oil pressure location, the stock gauge (in the cluster) is broken, so I needed it. Fun times with FC's.

I would agree that the back of the water pump housing is the best spot for an ELECTRIC gauge. On the S5 housing, depending on the cars options, there is already a flat spot milled that is the perfect size for a 3/8"NPT sender to fit. My only fuss is that I prefer a full-sweep gauge and in a larger size like 2-5/8". There are very few gauges that meet both of those demands and still ring in under $150, which is why I went with mechanical. My Autometer Sport Comp reads uber fast and was only around $60. It's pretty interesting seeing the thermostat open up and see the gauge go from dead to 185 in about 1 second.

well, my housing just so happens to be off right now! I think I will go ahead and tap it, and put a bolt in there with some treadlocker, so that when I get the gauge, all i need to do is to take the bolt out and put the sensor in.

I wanted to get this gauge, is it worth it? http://cgi.ebay.com/ebaymotors/STRI-...spagenameZWD1V

Also, I would prefer celcius reading. Is there any reason that going with an emperial one would be better? If I get an imperial gauge, do I also get an npt sensor?

Will that STRI gauge have different tap size than the cheap auto meter ones? Should I just get the auto meter? I dont like the fact that it's mechanical and isnt full sweep.... :(

Go to a parts store and get a brass plug of the correct thread to plug the hole, not a bolt. Brass plugs, like coolant sensors, use a tapered thread so that it seals more and more as it is threaded in. They cost less than a dollar and would definately be worth the trouble of having a leaky housing.

Those gauges look pretty nice. I have no clue what quality is like, but a full sweep gauge in electric would be nice. Another thing to consider would be the size of the gauge sender. Space is tight between the WP housing and the alternator. One more reason my mech gauge wouldnt work there.