Hi Jim i do not have any drawings but here are some shots.
The aircraft is looking a bit used at the moment 3 years + old and 52 flights its not far off a strip and repaint.
The bent header is from hobby king the rubber joiner to the exhaust box is a car water heater hose this i got from Super cheap Autos they have a big box and you rake around until you find the correct size.
its a lot more durable then silicone tube , so far i have replaced the car water heat hose once its quite heat resistant.
The box i made from a large ally box section i had in my spare ally box the ends i added and used pop rivets and heat resistant silicone to seal.
The stinger you can see runs down to the bottom of the box and before brazing with ally brazing you drill the holes in the stinger i think i used about a 10mil. drill with plenty of holes, and you can see the thick bead of ally brazing round the stinger head.
The stinger rests on the bottom of the box as a support or you can fix it in someway perhaps split the ends and pop rivet it to the bottom.
The ally brazing are the rods you can buy i have it on my other computer and if you get stuck i will look it up later for you.
Its a fluxless rod ( see video below ) and it melts about 350C below that of ally about 500c and you clean the ally to join with a stainless steel brush very well and i clean as i heat the surfaces up at the same time and then coat both surfaces separately by applying the rod to the surface avoiding the rod in the flame or a bit will drop off.
By touching the rod on the heated surface the rod will melt from the contact with the heated surface then put them together and melt the two coated surfaces into one with heat away from the joint and use a bit more rod if needed, you do not heat the rod but apply the heat to the material you want to join. Apply the rod to the hot joint avoiding direct blast from the flame the heat from the join will melt the rod you can drag the puddle of melted rod with a stainless steel rod if needed , its a little bit tricky but thats the business we are in but naturally if you have a $2000 Tig welder, lucky you.

PS.Also the tube joining the header has had the same treatment. IE. it go's all the way to the back of the box and inside the box it has been multi drilled so in effect there are two sound wave deadening parts to the box. where the exhaust go's in and then when it comes out.

Found this on my computer.
http://www.aluminumrepair.com/video_new.asp