Review on K&N Cold Air Intake Kit: Maximizing Performance, Boost Horsepower: Fits 2002-2005 Chevy/GMC/Oldsmobile (Trailblazer, Envoy, Bravada) 4.2L L6, Model 77-3036KP by Terry Keown

I am impressed with the difference in performance, even here in California with its stricter air quality regulations K&N kicked it out of the park! My '04 Trailblazer LS sounds 'evil' and I immediately noticed an increase in performance. Easy installation except that a hole must be cut in the round tube to insert the sleeve in preparation for the bend. With the specified 1.25" hole saw the hole was too small so I had to use my dremmel to sand and enlarge the hole and then use some lithium grease to insert the bushing. work completed.