Intent is to make the car more direct steering and lively. Don't want it harsh over bumps, and for sure not as much bump steer as the my XK had.

 

My 2011 XKR has no noticable bump-steer (German roads). If the suspension is good and correctly aligned, it should be OK on this front. The 5.0 cars are stiffer sprung than the 4.2 cars but again on the move, they are a nice balance between comfort and sharp handling. Around town, something more sedate usually works better though.

Mine came on Dunlops. They were perfectly fine on grip and safety but strangely dull. Eventually switched them out to the Continental SportContact 7 and they transformed the car. Much more fluid and "lively" and probably more absolute grip but even the ancient Dunlops didn't ever let go when they shouldn't have. Tyres have come such a long way in those last 15 years, finding a good set that suits you is highly recommended. The only down side of the Contis is that they are slightly noisier than the Dunlops, and the XK (my coupe at least) seems to let in more sound from around the back than expected.

Yes, find a good one and try it out.The X150 can still be a nice car to drive 15 years after its first release.

 

BC Racing coilovers?!?!

 

Steering... As you know, the right tire under the right conditions makes all the difference.
Those running all seasons will never see the handling gains of an ultra sport summer tire. And that width of that solid band of rubber on the tire tread has a significant effect on steering compared to those tires that don't. Load ratings have an effect as the sidewalls are stiffer.
Couple with that tire age, Not to be overlooked. I find after 3 years its time to change them up.
And I've been known to reduce tire pressures by up to 10%, depending on venue, temperatures, humidity.
Of course, if you've messed with the geometry with spacers... I think you're wasting your time.
Do you have 20s and 19s? The handling differences there are interesting as well.

Interesting that some of my friends with much more HP of course have me on the straights. The moment we get to winding roads, I'm right there. And those roads with sharp corners, I'm gaining ground and passing... its all in the tire.

 

Agreed. If the suspension is in good shape, change the tires. My F type had Conti Super Contacts when I bought it. They wore quickly and I bought Michelin Pilot All season 4S. Much much nicer ride, quieter. Any of these cars are faster in the corners than I care to drive. The cars get faster, my *** gets thinner. My XK had brand new Conti DWS06 installed, and I'm tempted to replace them in the spring with the Michelins.

 

You dont even need to look at a XKRS-GT, the 2008 XKRS has quite a few changes over the stock XKR - the suspension, drop links, roll bars, steering rack, brakes are the main ones for handling and I can confirm it handles like a beast - you need to remember Mike Cross and David Pook worked magic on this. Ben Barry compared it to a 599 GTB, you certainly dont need a XKRS-GT.

What does that mean for a non XKR-S? probably get better brakes and look at swapping over suspension parts from the R-S, Be prepared to be shocked at the price of a steering rack however.