I've got a Truck Avenger (not sure which one) on a 10k mile crate 350 in my 1985 K10 Silverado. It didn't seem like my secondaries were opening so I did some homework. I used the paperclip trick that the manual recommended and it looked like they were opening a 1/4 of the way at best. I decided to pop the cap on my secondary housing to check the spring which I expected to be black. Much to my surprise it already had the silver spring that I expected to replace the factory black one with. As an expiriment I took the spring out all together and put the housing back together. I took the truck for a spin up the steep paved road beind my house. It seemed like the secondaries were opening alot more that time but I didnt use the paper clip to be sure. My question is, what should have happened with no spring in place. I dont plan on keeping it like that but I'm putting the truck in the local fair mud run in a couple of weeks and wanted to find out if that was a ligitmate way to increase power just for the event. In the long run is there a way to adjust the secondaries to open sooner if the silver spring isnt cutting it. Sorry for the endless post. I would really appreciate any feedback.