overheating or getting hot at low speeds usually indicates the fan clutch isn't working or if it's an electric fan it's too small, at higher speeds usually the radiator is the problem, more of a get you in a direction to check things than a rule of thumb. The others gave great advice..1st the stock gauge isn't a true indicator of anything get an aftermarket gauge to get a better reading on the temp. EFI cars run at 210* normal temp. do all the other stuff already stated to check things, also check to make sure the air defelector is still on the car, it's mounted under the core support and directs air up into the rad..these cars are bottom breathers. A pressure test also may be needed and a check to make sure there is no leaves etc. trapped between the a/c condensor( if you have air) and the rad to block air flow. you haven't maxed the cooling system with your mods.