i think the DXM you wanna be dosing is the Hbr one. The polistirex time release mechanism (its basically edible plastic) probably isn't recommended for tripping, since when you trip DXM it's all about taking it on an empty stomach and getting it in you fast since the come up tends to take some time with DXM.
also, make sure that where your source of DXM comes from has only DXM in it and nothing else listed on the active ingredients.
be careful with DXM tho. i've had some good times on DXM, and i've also had some really BAD ones..