If I were going to try it, I would probably start with something like this - http://cgi.ebay.com/ebaymotors/Pierburg-Exhaust-Muffler-bypass-flapper-valve-RACE-NEW-/170558499080?pt=Motors_Car_Truck_Parts_Accessories&hash=item27b6142908 .It the first one I pulled up, I'm sure there are others out there. Would give you a sense of some engine breaking. Just make sure you don't place it any further than the first before the first muffler, or it may be a one shot deal!Ian