Hi,
My first post in years
That's about what I paid for mine many years ago. I measured, with a thermocouple at the bonnet vent, only a few degrees temperature drop before and after the job. Nothing to get excited about performance-wise, but the coating also keeps my manifold in good nick (coming 17 years now), so I would say 110 gbp should be well worth it.
Insulation wraps are the way to go if you really want to keep all the heat inside the pipes. But I heard stories about premature exhaust failures, so I never tried wraps.