D&D Exhaust

Big E

Donating Member
Just recieved my D&D 4 into 1 system. I was kinda shocked to see that diameter of the pipes were kinda on the small side.

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The above pic is the diameter of the header pipe that mounts onto the block. About a inch and a half. The lower pic is the mid pipe that mounts for the head pipe to the can. 2 inches in diameter. Due the diameters seem right. Is this system right for me? I plan on only the full system with a air filter and a remap. Thanks

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That does not seem to be to small. About average 2 down to 1 1/2. You need at least that much restriction unless you are running a turbo.
That seems to be right in looking at my Yosh. My partner is coming over with his busa it has an akaropvic. I will post that measurement when he gets here.
I know that it's not the same but most V8 engines only use 1 1/2 to 1 3/4 inch pipes on their headers.
Unless you go WFO 100% of the time, restriction is good. You need a little to keep a good power curve/band. 0 restriction only helps top end only. Most guys on harley who put on straight pipes have lost hp, not gained.

If anyone is interested in the system. I will most likely put it up for sale. Full system, stainless steel headers to a black satin faux TI can. 4 into 1. It is new with only one prob. When it was shipped, looks like the shipper packed it wrong. The inside of the can has little scatches and pits in the can about the less then the size of a US quarter. But it is on the inside of the can so the scratches will not show when mounted. I will most likely ask $425 shipped in the lower 48 states. I will have pics up Friday the 20th of December.

Eric of MD