I don't know where you're from but out here in cali we say a Flowmaster one chamber, two chamber, or three chamber. I would imagine that the 40 series is a two chamber, in which case I will say go for it. I had one on my 97 5.7 liter chevy truck, but recently changed to a magnaflow. I really like the sound out of both of them. The magnaflow is more mellow and "refined" something you would find on somebody older's car. The flowmaster is very "raspy" but drones on the freeway at like 2800 rpms. You should definetely look into headers for the vehicle, I have a set of Doug Thorleys and it made quite a noticable diference in power. Enjoy, and keep us updated with what you choose and your thoughts, I'm curious.