Okay, this wasn't my Evo, but I still think it's worth posting. I have a 95 Z28 that has run 12.2@113 in the past and dynoed around 350 whp, but I haven't dynoed it or taken it to the strip in a few years. In the past few years I've only driven it about 10K miles (mostly autocrossing). My Evo has trapped 112 the one time I took it to the strip and I've since added some mods, but I don't think I've gained that much power on straight pump. Well, the Evo has felt faster than the Camaro for the past couple years and I attributed it to just the difference in the torque curve with the Evo since I knew that both cars were capable of 112-113 trap speeds.

Today I put the Camaro on the dyno and it baselined at only 280ish whp! I couldn't believe it. Thought the motor must be hurt or something. As soon as we disconnected the air filter it instantly jumped to 350 something. 70 WHP from dirt on a conical K&N style filter accumulated over only 10K miles. This is a car that virtually never is driven in rain and never driven in winter. Unbelievable. After cleaning the filter and making a couple of tweaks on the tune, it left with a 358 whp dyno sheet.

So, the lesson today is keep those air filters clean!

 

That show's you the benefit's of proper mantinance procedure's.