4agze cambelt relacement question?

[lil]

This may be a stupid question but...

I'm going to change the cambelt on my aw11 mr2 and one of my main concerns is getting the cambelt tension right. In the Haynes manual it says you can use a belt tension testing tool by Nippondenso or something. Obviously I, or most people dont have one of those so I was wondering the best way to get the tension about right.

I am also going to change the waterpump and cambelt tensioner while i'm at it. Where is the best place to get these parts in Hamilton?