Boost Gauge and AFR meter

How much are they and are they easy to fit?

I've ordered a ScoobyECU from David Wallis (hope you can still supply ) for my UK MY95 and heard that it's best to fit the above. While I'm not a complete novice with engines, I don't really know my way around the piping on the car, so can any one point me in the direction of some simple to follow fitting instructions?

I've no idea yet on where they are going to be housed in the car. I'll think about that when I get the bits.

PS. I know what a boost gauge does, but AFR???? I know it measures the Air/Fule ratio, but how do you read it and what's "good" and what's "bad"? (I know... I'll do a search... ).