I've got catless DPs with stock midpipes and stock catback. On a true cold start in my garage (with the garage door open obviously
) I smell gas easily, because the secondaries haven't warmed up yet. Once they're warm, they reduce the gas smell significantly- you can't smell it from inside the car unless windows are all the way down and you're stopped at a light. Even then I rarely ever notice the smell and it is extremely faint.