I have to agree, I got TSR to re-con my coilovers on the GTR and they were fantastic, but since it has changed hands I have dealt with them a couple of times and got nothing but trouble and attitude.
My advise is, give it a go, the money you spend on labour is much better spent on tools. I have had 3 different workshops work on the GTR and ALL of them have managed to leave their mark on the car. BUTCHERS! Not worth the hassel unless it really is a job that is too difficult. Shocks on skylines are a sinch. 3 bolts and the whole lot falls out. If I remember correctly you need, jack, stands, 14mm &17mm spanners/sockets, spring compressors. Too easy.