The 360's have a TERRIBLE thermal design.
Adding ~ finger width to the height would more than solve the problem.
The heatsinks are WAY too small and the fan and ducting give priority cooling to the cpu.
I got one of those 'intercoolers' off eGay. Is loud as ****, but after modding my console, i cant afford it dying from heat.
Its usually the gpu that dies btw.
Spend the $20, forget the warranty