should I keep the AST?
 

What's the AST for? What' the advantage to keep it? and what's the advantage to take it out all together?

No responses...this expalains why you put it in the lounge too.

I think it just helps out a little with cooling your FD. I don't see why you would need it if you have other stronger cooling components. I'm personally just getting mine eliminated later because I don't want to spend the $ on one from Pettit and I'll be getting a better radiator and intercooler later.

The purpose of the AST is to allow small air bubbles that can form in your coolant to rise to the top and escape out of the system. Obviously you don't want any air in your system. As far as removing it, there is a lot of debate on this one. I personally went for the Pettit unit. My reasoning was I couldn't really prove that the car wouldn't be harmed by removing it. Obviously there are quite a few people running around without one to no ill effect, but at the same time, if it really isn't necessary, why did Mazda put one there in the first place? Their attitude when designing the FD was to put in as little as possible everywhere, so if they felt the car needed this part, thats how I feel.

well said Nathan, i agree with everything he said. You are safe withone and with out there is a slight chance of problems. I have also heard of people having to burp the air out of the system every month or so with removing this AST. I opted for a pettit unit too.