My 4L motor runs a just under 2.25" pipe, so it may not be all that small.
BUT I do see rather large diameter pipes on bikes a lot. So it may be a fair assessment they really don't like backpressure.
My 4L motor runs a just under 2.25" pipe, so it may not be all that small.
BUT I do see rather large diameter pipes on bikes a lot. So it may be a fair assessment they really don't like backpressure.
My memory is that every major change in shape, diameter, direction, etc... in an exhaust system sends a pressure wave back up the pipe. In a street car Catalytic converters are such a huge bump that past that you pretty much don't need to worry about anything other than having enough volume to flow your air. Direction changes, pipe size changes, etc... have little influence on power if you have the flow. On your bike system you have little waves at the junctions of the header tubes but the rest of the system is probably pretty consistent in diameter and straight through all the way out of the muffler with your last wave happening there. In adding the flex pipe and muffler you have lengthened your pipe, which changed the timing of the wave, and added a muffler with 180 degree direction changes inside-making a really hard wave at that point. A megaphone functions to change diameter and put a sort of stop on the waves travelling back to the engine. A megaphone right at your bike muffler tip leading to a large diameter pipe should allow a big factory high horsepower muffler at the end to work with few ill effects on how your engine runs.
Again, this is all from reading an exhaust design book years ago so my terminology may be wrong, but I think the general concept is correct.
When we shopped for our current house we were adamant that it would NOT be in a neighborhood with the dreaded HOA for this exact reason.
You are smart to what to keep the noise down as the facist house NAZIS cannot stand anyone who doesn't fit their Stepford world view......due note I've never lived with a HOA and do get why HOAs exist but sadly the people on the boards seem to get carried away.
Have you considered building a large-ish box that plugs onto the back of the car that has sound deadening material lining the inside and a flexi pipe outlet that you can vent the exhaust wherever you please
Tom
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