Volvo 670 with 2250

[JimT]

I'll repeat the same thing Waterloo said, remove all the cans and completely hollow them out. A hole through the middle might let the exhaust flow well enough, but the leftover material reflects heat back toward the turbo. And eventually the leftover filter material will build up with soot and that hole will slowly shrink in size.

The SCR can has nearly identical filter material in it to that of the DPF. Once the DPF is no longer catching the soot then the SCR can starts to do that job and, unlike the DPF, there's no way to clean it out. That's why it NEEDS to be hollowed out as well. Otherwise it will quickly clog up the exhaust system. At 25k miles that's a LOT of soot that has already been built up. The turbo will be the first thing to suffer as a result.

Like Waterloo said, if you have a straight SCR exhaust can then you can fairly easily break it up with a really really long drill bit, but if the pipes in and out bend then you pretty much need to cut it open then weld it back shut afterward.

The stuff breaks up fairly easily, but also produces some very fine dust. Suggest some kind of dust mask so you don't breath that crap in.