Just to fuel the slalom/stock issue raised in a parellel thread, I did some research into how Jaguars were slalomed when they were new. The following quote is from an article on gymkhana which appeared in the Summer 1967 Jaguar Journal. I think it proves my point that the cars weren't raced "factory stock" back then, and also that there's nothing new under the sun:
A Jaguar must run against competition such as the new Mustangs, Corvettes, Camaros with 427 cu in engines, and TVR's with 289's, etc. Most of this machinery runs fast, and to win with the 255 cu in of the 4.2 or the 231 cu ins of a 3.8 there is only one way to go: outhandle them, and outfinagle them on the pylons.
Setting up your Jaguar
Al Garz, who is Eastern Regional director for the Jaguar Clubs of North America, gave us much specific advice on setting up a Jaguar to win. Since Garz is an ex-dirt track racer who went on to drive at Sebring and numerous other events, he has accumulated an uncanny store of knowledge on the art of making cars handle right.
For the man who is beginning in the world of gymkhanas, Garz feels that the engine is really the last area where improvement is needed. Leave the mufflers on. Running with them off just draws complaints from the neighborhood without giving a corresponding power gain. If the course is not dusty, you can gain a fractional amount of power by running without air cleaners. The engine should be sharp, with plugs clean, set correctly and the carbs adjusted.
Tire Sizes
The main job is not to get more power out of the engine, but rather to get more of the engine power to the ground. One of the first steps this involves is tire sizes. You can easily go to larger than stock tire sizes. For an all out gymkhana car like Peter Schmidt's machine, Al Garz installed 9.00-15 Firestones at the rear and 8.50-15 Firestones up front. There are even more formidable tires around, but they are almost impossible to come by unless you have an in with the top dogs of racing. Even getting the 9.00-15's to fit involved the removal of the compression bumper (hardly recommended by the factory!)-the one that limits the upward movement of the suspension-since it's supporting bracket interferes with the tire. Some sheet metal lips in the wheel well area were flattened, and the fender was pulled out slightly to gain clearance. The entire job looks completely stock, and from a first glance, even a careful look, it is almost impossible to determine what changes were actually made.
Tire Pressures
Regardless of the size tires that you use, do raise the pressure enough so that the tires do not roll under and also so that excessive heat will not build up. .......
Dampers
On the car that Garz built up for Schmidt, he installed a set of Koni shocks as well as heavier stabilizer bars front and rear. The front bar is an 1/8th of an inch thicker than stock and has a diameter of .875 inches, and the rear one was upped in size from .750 to .920 inches. The new bars add to the Jaguar's roll stiffness and result in a much flatter type of cornering more suitable for gymkhana driving.
Camber
The factory camber setting should not really be altered but for gymkhanas some drivers believe a gain is achievable from a slight decambering of the rear wheels.....As Garz puts it, "If I don't get all of the tire on the ground, what good is it if I put on extra wide tires?"
etc.