Motor Authority points out that D3 has released stage 1, 2, and 3 kits for the Cadillac XLR-V.  Now, out of the box the XLR-V arrives with 443 elegant horsepower from a 4.4L Supercharged Northstar drivetrain, so it is no slouch.  The D3 packages manage to tweak that 443hp up to 525hp, or 575hp, or 600hp, respectively.  Nice icing on the cake indeed.
 

D3 Cadillac's Stage 1 XLR-V kit installed

Stage 1 Power Package: $1875.00  Application: 2006-2008 XLR-V
Description – This is our introductory package which includes Stage 1 and 2 Intakes and ECU Box. It is a relatively simple and quick bolt on package that will boost engine power to over 500 bhp. Installation only takes about an hour and can be installed with common hand tools. This is one of the largest performance gains you can obtain for your XLR-V with minimal investment.
Horsepower Increased to = 525+ bhp
Torque Increased to = 470+ ft lbs.
Includes Stage 1 and 2 Intakes and ECU Box

Stage 1.5 Power Package: $3,415.00
Application: 2006-2008 XLR-V
Horsepower Increased to = 545+ bhp
Torque Increased to = 500+ ft lbs.
Includes Exhaust System, Intercooler Lid, Spark Plugs, and ECU Box Tune Update)
Product Description – This upgrade will make your XLR-V accelerate like a true light weight sports car. Power to weight ratio is an astonishing 6.9:1! This is about as far as you can go running factory boost settings.

Stage 2 Power Package: $3140.50
Application: 2006-2008 XLR-V
Includes Intercooler Upgrade and Boost Upgrade.
*Does not include any of Stage 1 items*
Description – For those who are looking for a little bit more of an upgrade, but do not want to get into the motor, we offer our Stage 2 power package. This package includes our Intercooler Upgrade & Boost Upgrade. It will boost engine power up to 575 bhp and over 580 ft lbs of torque. *Does not include any of Stage 1 items* This package requires a PCM reflash to maximize tune and engine potential. Because of the high output of this package it is advised that brake upgrades are also considered at time of purchase.

Stage 3 Power Package: Call for Pricing and Details
Application: 2006-2008 XLR-V
Horsepower Increased to = 600+ bhp
Torque Increased to = 580+ ft lbs.
Description – This is for the enthusiast who wants it all. Each stage 3 package is customized to the individual’s desire. We cover everything from ported cylinder heads to rebuilt bottom ends. Also part of every stage 3 is braking system upgrades, wheels and tires (if big brakes are used) and any other custom modifications desired. This power package is rated at 600+ bhp. The Stage 3 power package is typically only done in house.

The Stage 2 appears to be in addition to the cost of the Stage 1, so to purchase the Stage 2 you would need to add the cost of Stage 1 and Stage 2.

I can’t wait to see what D3 has planned for the CTS and for the CTS-V. I think we may see 700 hp Cadillacs on the boulevard soon.

Motor Trend Magazine has a complete review of the D3 Stage 2 XLR-V HERE.