I just had the exact same issue (3 inch set) passenger side only. I called them and they claimed I was the first person with this issue ( yeah right) …
They hemmed and hawed, finally sent me a new pipe they said they tested before sending. They sent it next day got it in today - and same issue. Couldn’t get it down to the notch however, got it farther then the first one about a 1/4 of and inch from where it needed to be but had enough room to clamp it down.
I called them again to report the results and they said to take it to a muffler shop. Funny part is where it’s at it lines up with the mid muffler perfect. The drivers side that went on with difficulty but went over the notch was actually a 1/4 of and inch short of the front of the muffler where the one that’s not seated right lined right up. The band clamp covers the goof up. The rest of the pipes from the back of the mid muffler lined up perfectly.
I would not recommend these pipes until or unless they fix that issue … it was a real headache although customer service handled it - it wasn’t without a fight and they lied and said this was the first issue they’ve ever had and that clearly is not the case. If you decide to purchase I would have a shop install that way they have no excuses if shit doesn’t fit …♂️
One more thing my opinion: - the sound although is different than stock and the tips look a whole lot better it’s really not worth the money - if your thinking about this I would take a pass honestly…
