Hi,

Can someone give me some boring information on rear silencers?

I got a Straight through backbox a month ago and it was too loud,
so I got another one stamped JASMA (I know what this means) and it looks straight through aswell but quieter!

Are the holes in the boxes where the exhaust gases spread out to make it quieter?

 

The internal layout of even two apparently identical straight through boxes can be very different, the scoob 'rumble' makes the designs needed a little more taylored if they are to work both effectivel as gas pipes and also as silencers (if you want that).

The perforated tube (which is I think what you mean by the holes) al;lows the gas to expand into chambers to reduce the high energy pulse, sizing chape and absorbent material in the chambers can change the silencing characteristics.

Not all apparently straight through silencers are straight through, easiest way to check is to use a solid rod (garden bamboo) and see if it will go into the tailpipe to such a length that it must have exited into the inlet pipe!

Simon

 

Yeah, I got a bright torch and shon inside and I can see it is straight through with the holes around it.


What would be the difference between a straight through performance back box, i.e NINJA, and say what I have a JASMA approved back box?