Never tune by temperature alone. As long as you can see blue smoke (a thin trail is all you really need) coming from the exhaust pipe through the powerband/throttle range, you're fine, it means the engine is getting lubricant (not burning it all off by being too lean). That being said, I'd start to worry if you get up around 230-250 with the MIP guage (MIP will usually be colder than if you use an infrared temp gun, since the MIP is measuring it at the bottom fin, and the temp gun will be measuring it at the glow plug, where you want to be getting your temps from).