At 4 bars, sometimes up to 5 bars after 15 min of normal driving. Also spewing coolant from radiator cap. Im constantly pulling over to cool down and refilling coolant. I let the car cool down to get back to at least 3 to 4 bars b4 i start driving again. Any DIY thermostat replacements out there? I know this is a major issue and need to replace this asap. ive been negleting this issue cuz of the busy schedule but now got alittle freetime. Thanks guys appreciated.

 

Did you do any repairs or mods on the cooling system in the past, it sounds like you might have an air pocket trapped in the system which can happen with some mods if not properly bled. If you have not done any repairs in the past then the thermostat could be the culprit. Make sure both fans are working and coming on properly. The only other thing would be a bad water pump but those are very rare on these cars. I replaced my thermostat as it got stuck in the open position and the car was running too cold, opposite of your condition, turned out my Mishimoto rad spit out a piece of aluminum weld that got stuck in the thermostat and prevented it from closing.

 

The thermostat housing is easily located if you follow the lower radiator hose from the radiator to the block. I think it's most easily accessed from under the car. Drain all your coolant, remove the lower radiator hose, and replace the thermostat.
Are you sure you don't just have air trapped in your system? An air bubble can cause the blockage and will not open the thermostat. Also would cause the coolant coming from your radiator cap. You should try bleeding the air from your cooling system before replacing the thermostat, it may save you the headache as I hated changing mine.
Look up Billman's Cooling system bleeding guide here on forums, it is exactly what I followed and it has worked extremely well for me.
If you do choose to replace the thermostat, whether you have to or not, I'd say go for OEM, they are nearly fail proof-which is why I'm pretty sure you just have air. I went with the Mishimoto thermostat to match my radiator and regret it.
Good luck.