In my opinion coolant reroute is the most important cooling mod.
Results were good and I see 9°C less than standard system. Success!
I wouldn't even think of a real turbo on a 1.6 without a coolant reroute.
I did a coolant reroute and erratic temperatures have ceased. Car runs smooth as butter.
I'm very pleased with the reroute kit and would recommend it to anyone with a temperature problem.
I installed the re-route almost as soon as it became available. With all the boxes checked, I think I've finally got things under control.
I put the reroute on primarily to equalize temperatures across all cylinders. I noticed a small decrease in temperatures (~5° F) at the end of my track sessions.
I did notice that my fans did not come on at idle, at first I thought that I did something wrong but my car temperature was actually lower. The needle stayed midway instead of just above.
I had overheating problems when traveling through hot areas (>100°F), had to limit my speed and cut back on the AC so as not to overheat. Haven't had issues since, even in 112°F heat last summer.
The summmer heat would play hell with the power output of my mild-modded 1994. After the reroute, my throttle response, was crisper on 120°-ultra low humidity days on those long high speed trips to Santa Fe.
I noticed the #4 cylinder was a little lower on compression than the others about 6 months after fitting the turbo. I modified my fuel rail and rerouted my cooling system. Since I made these changes there has been no further detioration of my #4 cylinder pressure.
Whether or not an owner has a cooling problem isn't the real point. They may not overheat, but the heating/cooling of the engine isn't uniform with the front return of the original system. I'd say for those who run hard, especially in hotter climates reroute is a great idea, along with a better radiator.
After installing a traditional rear-thermostat reroute on the '92, I noted a decrease in normal operating temp (as measured at the stock CLT sensor at the back of the head) of 5-10°F on average, and also a marked decrease in the vehicle's propensity for overheating (which I define as >210°F) in slow moving traffic. These measurements were taken with a datalogger on the MS, so I'm fairly confident in their accuracy.
The rerouting kit achieves it's goals of using the radiator more efficiently and flattening out the cylinder to cylinder temperature. The kit sends coolant to the radiator consistently 20°F higher than the stock configuration while maintaining the same thermostat controlled temperature at the back of the head. The kit minimizes the temperature difference between #1 cylinder and #4 cylinder from 20°F in the standard configuration to a 5°F maximum. And that 20°F is a mixture delta, the actual delta is even higher.