All of those are more sportscars, the emphasis there being good handling rather than power. Musclecars have stuff like extra springs in the right for a better launch, rather than coilovers and sway barrs ;-)
The GNs are nice, minor tweaks for the 13s easily :-) GNXs are even nicer!
MagicM - if you're running a 1050 with heads to match, that counts as tuned :-D I've got 8.5:1 compression, but big valves, uprated valvesprings, mild cam, 750 vac Holley, Performer intake, cheap headers and Flowmasters.
With that compression I can nearly take a whizz in the tank to refuel!
The quickest street legal car here runs a Twin Turbo BBC, fitted into an Audi 80 body for consistent 8.6s. For street legal they have to complete a cruise that includes speed humps etc, and having seen it run it goes nice around town :-D
As for the Jag, good luck with the project, and I thought having 8 plugs was a pain, lol. The Rodders here seems to be using Volvo back ends more and more, the simplicity and strength of a solid rear axle seems to appeal more than the 'bling' of IRS these days ... and serious cars would quite often bend/snap Jag halfshafts as they were never designed for 700hp and 33" slicks.