DIY Exhaust Mod – Gain of 10+ HP!!!

[chipmunk]

Originally Posted by nieuwhzn

So what would happen if the slight bleed holes in chamber 1 and chamber 5 get opened up more? In first order this will let more of the primary exhaust go straight out of the tail pipes. This is almost the same as the exhaust bypass pipes on the PSE. The big difference is that more of the primary exhaust left (yellow) is going to 'hit' the primary exhaust from the right (red). This could lead to these two exhaust sources starting to 'beat' against each other, i.e. drone.

In the extreme, opening up the bleed holes in chamber 1 and 5 would effectively give you a free flow system. You would however have to remove the box to get to the ends, or cut holes in the casing.

I am not sure that the mixing of gases causes the resonance. I have just removed a Toyo free flow exhaust from my car due to the resonance (it was so bad my wife refused to travel in it) and there the two pipes and silencer boxes are completely separate ie there is no mixing of exhaust gas from left and right cylinders. I have had resonance before with stainless steel boxes and think it must be something to do with the vibration of the casing. I don't believe that modifying the std box will ever give you resonance, but then that's just my view.