Aye, Gav will set you up with as simple or complex a boost gauge as you want
For just basic boost levels the TIM127 gauge is ideal for around £20-ish+£7-ish for the pod (the bit it sits in). It reads upto 1 bar and the scale is very easy to read.
If you wanna go all fancy and digital then an SPA gauge is good for over £100. This also read charge temperature and you get things like maximum boost level, average boost as well as the ability for it to drive things like boost adjusters to raise/lower boost according to charge temp....
basically cut into the hose between intercooler and inlet manifold and fit large metal t piece to rejoin 2 halves and fit dump valve into remaining junction on t piece, then run vacuum hose from top of valve and join into a vacumm pipe coming from the inlet manifold then ur off puttiiisssssshhh. you get fitting kit usually from who evere you get dump valve off.