I have a Crimson Pearl XLR I custom ordered and is scheduled for build on 12/20/04. Have been researching some planned custom mods after I take delivery and thought others may be interested in a couple of the items.

Lund Cadillac in Phoenix offers (2) CAT-Back Exhaust Systems. One uses a rectangular dual tip design (similar to the Foose/Lund XLR project recently on Rides) and a second version with round tips. Price for the rectangular is $1,995 installed and they say +20HP plus a better performance tone. They also offer a complete chrome grille for $1,895 installed. I believe they also will sell them as boxed units so an owner can install: Lund Performance Parts, Blake @ 602-375-4355.

Rectangular Tips CAT-Back Exhaust System:
http://www.lpestore.com/ACCENLARGE.CFM?ID=367&dlr=LUND

Round Tips CAT-Back Exhaust System:
http://www.lpestore.com/ACCENLARGE.CFM?ID=368&dlr=LUND

Chrome Grille:
http://www.lpestore.com/ACCENLARGE.CFM?ID=365&dlr=LUND

I can guarantee you one thing, no way are you going to pick up 20+HP by freeing up the exhaust. I own a Viper and all the aftermarket CBE manufacturers make claims - none, zero have been substantiated. You should change your exhaust only because you want to change the note. I would also advise you to listen to the exhaust you want on another XLR to see if you would like it. If you think you are going to gain HP by making the change, save yourself some money.

Corsas website has dyno test with thier systems with gains of 22 HP for my 2000 STS. After seeing how small and restrictive the stock system is, I bet it would add quite a bit more power.

Over the years I've installed both cat-backs as well as full, header-to-tailpipe performance exhaust systems. The most recent being an 03 Cobra on which I installed a Magnaflow catback and an aftermarket X-pipe. The gains were clear and backed up by a before/after dyno pull.

Horsepower gains are driven more by your vehicle's stock setup and power output rather than by the aftermarket part in and by itself.

For example: The 03 Cobras are deep breathing, factory supercharged motors that profit from opening up the intake side by removing the factory-installed silencer and restrictive filter element. That modification alone is a proven way to add 10-25 horses, depending on the type of CAI. Once you do that, opening up the exhaust side provides the higher air volume a place to go once its utilized.

That engine is one big air pump waiting for someone to open it up. The factory output of the 03's is a published 390 horses. With a few dollars in modifications, many owners are enjoying upwards of 475 horses, and we are talking about a 281 cid motor, not much different than our own.

Our XLR's may not be as restricted, so a catback alone may show little or no real gain, except for tone and sound level, especially if you have not yet explored the intake solution first.

The first thing I did when I picked up my XLR was to run down and buy two replacement K&N filters for the airboxes. Throttle response seems to be a bit better, however that's a relative statement.

As soon as the weather clears around here I intend to check their effectiveness with before/after dyno pulls. That should provide a pretty good benchmark of the car's capabilities, as well as an indication of just how accurate the factory's published numbers are.

Would agree, opening up restricted areas adds HP, but I would not rely on a company's claims of added HP. Corsa claims 20+ for the Viper - nobody, I repeat nobody has seen this gain. Typically 1 to 3 which would be in the range of error. You just have to know where the restriction is. On the Viper adding K&N and smooth tubes adds about 10 but a cat-back only adds essentially zilch.

Would agree, opening up restricted areas adds HP, but I would not rely on a company's claims of added HP. Corsa claims 20+ for the Viper - nobody, I repeat nobody has seen this gain. Typically 1 to 3 which would be in the range of error. You just have to know where the restriction is. On the Viper adding K&N and smooth tubes adds about 10 but a cat-back only adds essentially zilch.

Agreed, the manufacturers love to throw around numbers, however if you take the time to actually test the effectivness of their product you will more than likely be disappointed.

I would guess Dodge did a good job in plumbing the backend of the Viper, so all you need is to add some more air up front and you have a solid gain.

I agree with MSWAIM. I had a 2003 Cobra and for about 1500.00 I had that engine up to about 500 horsepower. The gains on the XLR will not be that dramatic, but I'm confident the biggest gains are on the intake side. That was certainly the case with the Cobra. Changing the throttle body, the air cleaner, the 95 mm mass air kit, etc. was where the power came from. I changed the exhaust from the cat back and was going to do headers, but was talked out of that by a mechanic that told me that I could do many other mods for much cheaper that would give me more than headers.