 SPA digital dual temp gauge...  SPA digital dual temp gauge from Bimmerworld reads oil and water temps. It includes two 1/8" NPT temp sensors that plug into the gauge's wiring harness, while the other end of the harness plugs into the back of the gauge |  For the water temp sensor,...  For the water temp sensor, we took our oil drain plug and carefully drilled and tapped a 1/8" NPT hole using a drill press. We then applied Teflon tape to the threads and screwed the sensor into the oil drain plug. Drill perfectly straight or you'll run into problems |  We had previously removed...  We had previously removed and capped the coolant lines from the throttle body to keep it cooler. One of those lines ran under the intake manifold and toward the middle of the cylinder head, which we had capped with an oil drain plug. This turned into the perfect location for our new water temp sensor |
 We purchased a new drain plug...  We purchased a new drain plug from UUC (right) but with a built-in magnet to capture metal shavings from the engine. We also ordered UUC's billet aluminum oil filter housing lid. It has two pre-drilled 1/8" NPT taps to let you fit either an oil temp or oil pressure sensor, or both |  The UUC lid is a 60sec installation,...  The UUC lid is a 60sec installation, and potentially saves hours installing an oil temp or oil pressure sensor elsewhere |  Our UUC lid, PWR radiator...  Our UUC lid, PWR radiator and Bimmerworld upper hose installed. While you need to muscle the hoses onto the thermostat housing, we found shaving the inside edges with a razor helped immensely |
 To install the gauge in the...  To install the gauge in the cabin, we had to find a way for its wiring harness to reach the sensors. We chose to go through the driver's side floorboard, and started by removing two screws holding the cover under the steering wheel |  With the two screws removed,...  With the two screws removed, we pulled off the cover |  Since we're using the gauge...  Since we're using the gauge for testing and the car isn't boosted, we refrained from installing it on an A-pillar mount. Instead, prior to reinstalling the driver's side cover, we attached the gauge by drilling a couple of holes and mounting it to an Auto Meter carbon gauge pod |
 Because the cooling system...  Because the cooling system wasn't under strain in third and fourth gears, it didn't show much change. But under a heavier load in fifth gear (over 120mph) we see a more consistent power curve with the PWR radiator (see graph). It averaged 218whp through the gear, versus 214.9whp for the stock setup. It also gave a 0.15sec improvement in acceleration from 122-150mph | | |