Do you have to weld the Magnaflow tips in place? On my 04 M3, the tips are replacable with a screwdriver.

Yes they will need to be welded on. The mechanic said he may have to modify the pipes so they don't stick out too far. I forgot to mention, his installation cost will be between $50- 75 , depending on how much he has to modify the pipes. Add this to the cost of the tips($160) for a total of $220-240.