Parts help.. Exhaust Augmentor inserts

Ok.. this may be more appropriate in homebuilt because its going on an
experimental, but I wanted to pick owners brains regarding a certified
part I want to utilize.

I got a good look at a friend's twin bonanza the other day, and really
liked the exhaust augmentation that it uses to pull air from inside the
cowl. The T-Bon had what looked like stainless with some sort of slotted
mesh inside of it that helps break up the sound pulses.

Well.. several other rotary engined fellows have fashioned their own
crude exhaust augmentor tubes and have had workable results so far in
flight. Enough that I located and obtained an augmentor tube off of ebay
(no part number attached) and when it arrived it looked perfectly
useable.. except that there was no slotted insert.

Straight pipe would be "ok" but the insert would be better (from a
temperature and noise standpoint). Anyone know of the proper name for
this slotted insert so that I can try and find one..

Even better.. someone know of an old derelict aero-commander or twin
bonanza (or similar steed) with weeds growing through it.. that the
owner might part out an entire tube with insert? This might save me a 4
hour each way road trip to Air Salvage of Dallas.

Dave