ok here goes no help from here so ill do it bin ages on the net like a geek found the info yamy dt125re
undo three phillips screws from head light left right and top of front mud guard pull down what looks like a rubber condom housing some wires and plugs . checked on this so dont worry theres a white plug with four wires that come from the frame side of the bike but on the other side of plug(towards the clocks) theres only three wires so the spare black and green wire that goes to nothing pull out from white clip and solder an extra foot of black 7.5 amp cable ! not bell wire add one ring terminal and i earthed mine on the chassis bolt which holds the rad support onto the frame connect up seal water tight and put it back together .
reasults are a louder more proud growl .( 125 yeah i know ) but the power increase and pull are amazing ..
usually i get 65 70 on the flat if im lucky ( no head wind jokes ya cunts) but now it pulles 65 up a very steap hill near where i live very impressed time for an accident now!!! lol
anyways hope this helps others too >
ps i do have a dep pipe so dont think standard stuff will breath the same guys must have good air flow
even talked to a guy on the lights who had an r1 and said that goes ok dosnt it for a baby so im fecking chuffed >