Go to tirerack.com and you can see various wheels right on an XD-type. I would stay away from 18s as this will kill the ride.

 

Frank, something you may want to consider is buying an X with a 3.0 liter, especially with a manual transmission. Would be the simplest and easiest way to get more power. Plus, everything would be fully integrated from the factory. Plus, if you would get a Sport model it would already have 17" or 18" wheels. Before I bought mine I droive a 3.0 with an automatic and also a manual transmission. To me the difference between an auto and a manual was pretty dramatic. I don't know what it might be between a 2.5 auto and a 3.0 manual, but I bet it would only be magnified. Would save you quite a bit of time and hassle and you might also come out ahead financially as well. At the very least hunt a 3.0 manual down and take it for a drive to compare.

I have the Borla mufflers on my car and I can't say that it did anything for performance, but to me it looks better and sounds more aggressive without being obnoxious.

I have the stock 18" Aruba wheels and I have bent a couple, but the roads here in Wisconsin are brutal. I can't say that I am dissappointed with the ride on 18" wheels, but that is pretty subjective. Good luck with whatever path you choose.

 

snap

 

Definitely get the Mina exhaust. I have a 2002 3.0 and it gives it a great sound. My jag has more of a growl now when before it was like a purr. Also, upgrade your air intake. This has mixed reviews because most say to leave it like it is, modify the air box a little, or get a new intake. I, like some, went with the Spectre intake. It goes very nicely with the sound of the exhaust but neither will give you more than a couple horses.