D3-Tuned XLR-V Cranks Out 600 HP; Brake Upgrades "Highly Recommended"SCadillac tuners D3 Research have introduced a new three-step tuning package for the XLR-V that results in a Michelinferno-inducing 600 HP in top trim. Unfortunately, that sort of output isn't available with just a few simple tweaks: A complete engine rebuild is part of the package required to extract peak performance from the 4.4-liter Northstar V8, and owners are urged to opt for the "highly recommended" brake upgrades as well. Customers not wanting to go quite so far can opt for the stage one kit providing a new air-intake system, reflashed ECU, "performance spark plugs" and a high-flow exhaust system, adding up to a still-healthy 525 HP. Of course, if you just want your base XLR to look like a D3-tuned XLR-V, you can buy body trim and emblem kits separately. Poseur. [Motor Authority]