I think the performance upgrade for the 8 IS an R.

 

Unfortunately it is a well known fact the R is easier to tune and the best way to tune an 8 is to part ex it against an R........ This does not mean the XK8 can not be tuned it just costs a lot, when I did my track car I wanted to use an 8 and to make it faster than an R even a mildly tuned R, but getting there cost a lot of money and is totally cost prohibitive but if it's pissing rights you are after then fill your boots, most will think you are barking, quite a few think I am

 

Well, I see many of you talkin' and not so many really testing. Those who tried the chips didn't keep any kind of record on MPG or dyno tests or accel times.

At this site: Performance Chip Reviews & Guide for Car & Truck

They tested a number of chips on 4 different vehicles. The GTE chip was hands down the winner. True, most of the rest ARE garbage, as we could expect. However, a bit of objectivity would go some ways to the truth and give us a leg up.

I for one would like to find out more about the good chips and what makes them tick. That would be worth reading for all of us.

 

Well, if you want something that actually will work, it's not a chip but an ECU re-map, or a complete piggy-back ECU...

There is a reason why a tune from ETG or Eurocharged is >$1000, or why a piggy-back ECU from Arden is >$5000, because they actually work.

A generic plug-in chip for $100 off ebay is snake-oil, make no mistake.