hello gents,
ive got a few questions about tuning my 1999 xkr and was looking for real world experienced answers, not the sales blurb you get from retailers.

the car is in good shape pretty much all the mechanical maintenance and upgrades have been done and im now looking to make it a bit different and faster.

so, the plans

1. lower the car . I want the ride height slightly lower but I don't want to ruin the ride and make it bumpy. the car is also cats equipped so would lowering springs effect the cats system and what springs offer a lower stance with an oem ride?

2. larger crank charger pulley.. I want to up the charger spin rate for a bit more boost, can anybody advise on a good quality pulley that wont over rotate the charger but will offer reasonable gains. also will uping the charger rate require a remap. sellers of the pulley say the oem sensors will recognise the additional manifold pressure and fuel accordingly. is this correct?

3. Exhaust. I would like a mean v8 growl from the big cat but without it being unbearably loud and droany on a long cruise.
additionally I've been told its easier to loose power than to gain it when messing with exhausts, back pressure and flow.. is there anything I must not remove or is it not an issue on the xkr?

sorry for the long winded questions, I just want to be sure im doing the correct things as I don't want to spend a fortune making my car worse.

thanks,
craig

 

This may help with item number 2: https://www.jaguarforums.com/forum/x...entures-46329/

 

I'm fairly certain all of the shorter springs that you would use to replace the OEM are stiffer, and they should be. If you lower the car, you'll want stiffer springs to keep it from bottoming out, I would think. Perhaps someone will correct me.

 

I have to have other people do these things, so here is my summary of costs (parts and labor) plus benefits:
1. Lowering springs = $860 . You'll be doing this for looks as no one has endorsed this as a major benefit to handling (and I'm a former Porsche Boxster driver so I'd do it if it made a substantial improvement).

2. Supercharger = $1,100 for the lower unit, which is a more expensive part but doesn't require any tedious snout grinding.

3. Exhaust = $250 to $1000. Like the springs, this is aesthetic. I had a shop remove just two rear mufflers, then four. Four was hilarious but too much noise, especially highway. With rear muffler delete you'll hear growl and burble while casually driving and people behind you get the best sound when you floor it.

Best to make sure all the usual parts and systems are in top shape. I'd do mods but strong maintenance always comes first as its my daily driver

 

Lowering is possibly a bad idea since your oil cooler is already perilously close to the ground and it doesn't do anything for performance.
On the exhaust - as Weisberg says it's just for fun.
That just leaves you the s/c pulley.
Bear in mind she's getting on - don't know the mileage - and is maybe thinking of a graceful retirement rather than finding herself a toy boy !