Okay, here was the problem that I had. Whenever I drove the car after parking the car I would notice a combination of coolant boiling in and spilling out of the resevoir tank. I've tried topping off the coolant, changing the radiator hose, and replacing the thermostat (not OEM).

Still the problem remained, then I took it to my mechanic who's worked on rotories for 17 years and here's what he suggested: to modify my thermostat by cutting the 2 flange that's keeping the spring in place and removing bascially everything in the middle. What only remains is the O-ring and metal ring of the thermostat.

The mechanic said most likely the original problem was with the thermostat being that it was not OEM and that if I wanted to modify the thermostat, it will lower the temp and resolve the probem.

Result:

The car runs cooler and problem seems to be gone.

Current Setup:

S5 TII
Knight Sport Turbocharger
Knight Sport ECU
Knight Sport Dual Pulley System
Koyo Radiator

 

So why not run an OEM thermostat?
if you do a search I am sure you will see lots of info on running non oem vs oem and/or no thermo at all, there is lots of talk about it.

 

That's actually a mod listed on MazdaMotorsports.com recommended for rotary racecars that run high rpms for long periods of time. According to them, running a gutted thermostat works even better than running no thermostat because it adds a little pressure by having to go through the smaller orifice. It oughta work fine, it just won't heat up as fast in the winter. If you're running straight water, drain and refill with antifreeze mix before winter though, fc3spro.com has some nice pictures of a rotary engine freezing and demolishing the engine.

 

I was going to just get an OEM thermostat, but even so the mechanic suggested the mod because it'll help the car run cooler.

 

Yea, I thought i saw that article before. It looks like it runs well and thanks for the info.