free DIY better flowing stock exhaust.
free DIY better flowing stock exhaust.
Allright, for those of you that can't afford an exhaust system yet, this DIY is for you. As we know that Evo exhaust has a flapper door inside the muffler to control backpressure. The door opens at higher RPM. So, why don't we keep it open for better flow? Here's how! Keep the flapper door open with a long screwdriver. Take a drill, and drill through the muffler and the door in a straight line. Finally, attach a screw to the muffler and the door to keep it open. That's it! Now, this is just one of those , you're bored as hell and have nothing to do project. For those of you that has **** to say about this, please keep it to your self. 
Just trying to help!
Just trying to help!
A few of us with even more time on our hands have removed the flap entirely. It took me a few hours of prying and twisting before I finally broke the flap off its hinges... and then the spring--which is not ferromagnetic (not removable with a magnetic pickup tool) fell into one of the inner chambers and it took another couple hours of shaking the muffler around before it fell out. I don't really know if it produced any power gains, maybe a handful of horses at best. In hindsight, I would have been better off just buying an axle-back. But if you have a few hours to kill and nothing better to do...
Originally Posted by kuniboy
For those of you that has **** to say about this, please keep it to your self. Just trying to help!
Just trying to help!
Excellent mod! So, does the exhaust sound a lot louder now?
I notice that my exhaust is MUCH louder on hot days when the car is fully warmed up (like after my 1 hour drive home from work) particularly at idle/low rpm. I've always wondered if the flapper door somehow tends to stick open in these conditions. The sound isn't objectionable.. in fact, I think it's just right. If screwing the flapper back with your mod gives me this all the time, I'm game for trying it.
I notice that my exhaust is MUCH louder on hot days when the car is fully warmed up (like after my 1 hour drive home from work) particularly at idle/low rpm. I've always wondered if the flapper door somehow tends to stick open in these conditions. The sound isn't objectionable.. in fact, I think it's just right. If screwing the flapper back with your mod gives me this all the time, I'm game for trying it.
