IF THE GARDEN-VARIETY 2005 MERCEDES-Benz SLK350 doesn¡¦t satiate your need for speed, hang in there until November and your prayers will be answered.

That is when the SLK55 AMG hits the U.S. market, powered by a hand-built 5.5-liter V8¡Xthe first V8 in an SLK and the only V8 in the segment. Mercedes says the engine, producing 362 hp and 376 lb-ft of torque, should rocket the SLK55 from 0 to 62 mph in 4.9 seconds. That power gets to the 18-inch rear wheels via a short-throw six-speed manual transmission or the AMG Speedshift-controlled seven-speed automatic.

Body and chassis modifications include AMG front lip and rear deck spoilers, and AMG-specified suspension, exhaust and composite brakes. Inside, an AMG steering wheel, instrument cluster and sport seats set the car above its everyday SLK siblings. Pricing will also be up there, starting in the low-$50,000 range.

If the SLK55 AMG isn¡¦t fast enough for you, Brabus has an answer with its SLK 6.1S version of the 2005 SLK. The German tuning company has gone to work on the already powerful V8 engine, extending capacity to 6.1 liters and adding a raft of beefed-up components, including lightweight pistons, new piston rods, higher-lift camshafts, freer-flowing exhausts and recalibrated electronics. The result: an 83-hp and 92-lb-ft increase in output to 445 hp and 468 lb-ft of torque. Acceleration is in the supercar league, with Brabus claiming a 0-to-62-mph time of just 4.3 seconds and a top speed of 190 mph.

Want it? The cost of the engine upgrade alone is about $36,000 (e29,050). Brabus will also sell you a myriad of suspension, exterior and interior modifications for the SLK.