Radiator Or intercooler
 

So pretty much I was wondering which would make my evo x faster? A new radiator or intercooler. Thanks

These are more about making the evo run harder. Out of the two.. i would go with a inter cooler. You will notice that even without a tune... you will feel the car just go stronger for a longer amount of time.

You can get your radiator upgrade once you go to a bigger turbo or when you really need it.

A more efficient intercooler will give you gains. Simplified, The more air you can pump through your motor the more power you have. This is achieved by an intercooler in two ways. One, less restrictive end tank and core design. This allows more air to flow through the intercooler. It's a double edge blade though. The purpose of an intercooler is to cool the air being pumped into your motor. If the air is passing though the intercooler with no restriction there is no time for heat transfer to occur. Warmer air is less dense which gives you less volume. Cooler air, more volume (this is the second way a intercooler can help). You want a balance between the two. There are several intercooler designs which, depending on your use, I could recommend one but that is a separate discussion. The radiator, unless your cooling system is at capacity, will net zero gains. In fact there's a possibility (although unlikely as there's control mechanisms for this) it will keep you from reaching optimal operating temperature and you will see negative effects. Hope this helps, I tried to keep it simple so feel free to post more questions if you want more information.

Intercooler. The stock evo cooling system is already pretty robust. A radiator will give you absolutely no more power. Only let you drive the car harder longer if the stock radiator cant keep up, which isn't usually the case for a street evo.