ive both driven and been passenger in so many dozens of tuned 4wd turbo cars now that I really have lost count and my personal experience is that 400bhp ones drive themselves so well it pretty much bores me and that 600 bhp ones are as much fun as a 300bhp turbo hatch but far far dearer to run and also far harder to find somewhere to use them properly. And yes they of course are quicker if you care about lap times.
For example a few months ago a mate of mine asked me to take someone out in his over 500bhp escos to show them what it goes like.
I came off a big roundabout by morrisons (in Germany obviously or it would be naughty
Lol) and gunned it in 3rd from 60mph, then went flat out through 3rd and 4th till I topped 4th out at well over 140mph. Which I decided was as quick as I wanted to be going on that road which if it was in this country would have been a 50mph limit and potentially an easy place to get nicked. When I backed off I was still alongside morrisons. Literally had only gone the length of the carpark and shop and was going too quick already.
Its just pointless unless you happen to own your own very long stretch of road IMHO having that power in a road car. I've not even bothered taxing my own 500bhp or so sierra for years for the same reason. I just don't have any real use for it.
Hot hatches are just more fun to me and being so much more affordable means I can use them far more often.
Aydon is obviously quite new to modified cars so he hasn't been through it all yet but eventually he'll realise the pointlessness of chasing numbers too I'm sure just like I and nearly everyone else tends to do and just concentrate on what is fun instead.