Down on power?

I've finally found the time to fit my 200tdi after fully rebuilding it, it runs like a charm, starts on the drop of a coin, smooth and no smoke but it seems a little low on power, I can't seem to get it past 65mph, which was the top speed of my old 2.5na so something seems weird to me. Any ideas?

Might sound silly but is it revving flat out? if so you need to look at tfer and gbox ratios, get the serial numbers and look on ashcroft site for details.
If its a really low ratios tfer box 1.6 they are worth quite good money.