I decided this was quite a cheap and easy mod, one that I could handle fairly easily, and from what I have read gives a reasonable return on the investment, but more of that later.
The instructions that came with the pulley were reasonable, although I found the "Vacation Pics" far more useful, definately worth looking at before starting.
After removing the engine cover, and front air intake section, it was very easy to slacken the belts off and remove them. I don't have access to a belt tension measurement device, so what I did was to measure the deflection on the longest run of each belt with a good press of my thumb, and use that as a reference. Make sure you slacken the belts right off and don't try to pry them the last little bit.
Now for the painful part: with the car in 5th gear and the handbrake tight on, use a 22mm socket on the pulley centre bolt and with the longest lever you can find pull as hard as you can. The first time I tried this my hand slipped and took the skin off the back of my hand, so after cleaning up and this time wearing gloves, I puilled even harder and the bolt cracked loose. Take the bolt out, and with both hands slide the pulley off, don't try to pry from one side as you can crack the plastic engine cover behind it. As you slide it off, keep an eye out for the shaft key, which may or may not fall out, it didn't for me though.
Clean the end of the shaft up with a clean lint free rag, if you look inside you can see the timing belt. Slide the new pulley onto the shaft, taking note where the keyway is for alignment. Put a drop of oil on the bolt threads and on the underside of the bolt head. Then tighten up finger loosely. This part confused me, as the Perrin instructions stated the tightening torque should be 90 ft-lbs, but the manual states 132 ft-lbs. I know there is s difference in the material, but I can't understand why the big difference, maybe someone can point it out ?
Anyway, going by the manual, I went to 130. I wouldn't advise doing this without a torque wrench, as 130 is very tight, and it would be hard to try and guess.
Replace the belts and tighten until you have the same deflection as before. replace the belt cover, the engine cover and the intake. Then go drive !
My first impressions are that the engine seems to rev quicker now, the gas pedal seems more sensitive. Of course this might be because I've read that this should happen, but it does feel that way. The local track is closed for the winter now, so I can't prove any performance improvement, but my butt is happy !