From what I understand it just makes the coolant system easier to bleed, you don't need the hose.

 

Samco now makes silicone hose caps so you can delete the upper hose without having to ever worry about it leaking.

 

Nice, just did a quick search and came up with this. Sean can you verified for me if this is the correct size for our car.

http://racebikebitz.com/index.php?ro...product_id=590

 

It bypasses the radiator and allows a portion of coolant flow directly from coolant return pipe to the water pump suction.

It allows for a quicker warm up of engine for emission purposes, this is why not needed especially in warmer climate areas.