XK8 evolved from DB7

The1997 Jaguar XK8 was a re-engineered and tweaked evolution of the Aston Martin DB7, which itself was a restyled Jaguar XJS.

XK8 performance mods.
Replacing the restrictive stock exhaust manifolds with tubular exhaust headers such as used on the 2005 -2009 Aston Martin Vantage V8 will help greatly. An electronic control module to allow manually choosing shift points would also be a huge benefit. Lowering springs that lower the car about 1.5" will give the car a more racy look and help the handling.  

The factory optional wheels were 20" wheels. 20" wheels look good on the XK8, and in my opinion 21" diameter wheels look even better on the these cars. My XK8 has 20" diameter wheels that are 8" wide front wheels, and 10 wide rear wheels.


                 
1998 Jaguar XK8 Convertible.

The styling is still considered sexy, sleek, and classic. It has rear wheel drive with 4 wheel double wishbone independent suspension and 4 wheel disk brakes.

State of the art engine.
An all aluminum fuel injected V8 engine with double overhead cams, variable valve timing, and distributorless coil on spark plug ignition system. An engine designed by most of the same engineers that designed the legendary                                               Jaguar V12.
 
German ZF Transmission
A German ZF brand 5 speed automatic transmission. This is the same ZF model 5HP24 as used by BMW and Audi on their V8 engine cars. 
Dana 44  rear differential.
The Jaguar XK8 uses the same Dana 44 rear differential that the V12 engine Jaguars used. The Dana 44 differential has                                      been used on all Dodge Vipers and C4 Corvette ZR1's as well. 
Wood grain and leather interior
The interior is adorned with massive areas of real wood and  leather. There is a wood panelled dash board, wood on the center console, a wood rim steering wheel and a wook gear shift knob. You just won't find wood in the interior of  Vipers or Corvettes. You have to look to cars on the order of Bentleys and such to find such lavish interiors. 
Added XK8 Driving Excitement.
   Most XK8 owners  have never explored the performance potential of the  XK8. To get driving excitement from the XK8, you must push the button near the  shift lever that puts the transmission into the sport shifting mode. Make sure you have it in sport shifting mode. Now, when you floor it, the engine will rev up to redline(6800 RPM) before automatic shifting. Automatic downshifting is not as intuitive. For automatic downshifting. push the gas pedal down as far as you know from practicing with it in sport mode, will get it to downshift, then it will take about a half a second before it downshifts, but when it does, it will drop down about 3 gears and take off like a rocket.  When first practicing this, try holding the gas pedal about 2/3 to 3/4 of the way to the floor. The sensation of this half second or so lag time for the automatic downshift is probly not unlike turbo lag. While it takes a little practice to get the hang of this automatic downshifting with the lag time, it's really no more difficult than practicing to get good at a video game. With practice you will get a feeling for how far to depress the gas pedal then hold it there until the downshift occurs(you don't floor it for most situations).  Again, expect a half second or so lag time before the downshift occurs.
    For those of us who grew up driving automatic transmissions that had a vacuum modulator to determine the downshifting, the sensation is like a vacuum modulator that had a small vacuum leak causing a late downshift. So why does a modern car like the XK8 with electronic controlled shifting have this lag time? I can only speculate that this transmission, the ZF model 5HP24 which was also used on the BMW V8's, may have been originally designed for BMW and then Jaguar having overspent on the engine design went looking for an off the shelf already designed transmission to bolt to it, and therefore using shift programming that was taylored to the BMW application.
    Once you master the downshifting technique with the transmission in sport mode, driving your XK8 will be a far more exciting experience.  In my opinion, when you drive your XK8 using this technique, it sounds not unlike a crotch-rocket motorcycle reving up through the gears.