I've taken the quasi cold air/air muffler/water bypass off my Pro5 for the following reasons: After long trips that part of the airbox gets really hot since it's over the manifold and radiator. Also it weighs ~ a pound. Like Mah P5, my car now has a little better throttle response with a little growl. I wouldn't recommend to ride around in the rain & puddles because there is better chance of sucking water in. Also that chimney part of the airbox is sucking "dead" air. Dead meaning warm air sitting in the engine bay. The AEM short ram intake sucks "dead" air too. I'm waiting on competing companies with dyno results before I buy a CAI. I'll be damned if I spend $300 for a 2-5 hp increase. I was happy to get a moderate hp, torque, and mpg increase with the K&N drop in air filter. I couldn't beat it for $34. Also I don't have to worry about that maintenance item since it is warrantied for 1,000,000 miles.