Bought some quad tips for an exhaust i'm yet to mount. Here's what it looks like mocked up on the stock catback. The length is too long and would definitely need trimming- 6.5-7 inches total would do it- looks ok in these angles but in person it sticks out beyond my rear diffuser, about 1.5 additional inches of length compared to how far the stock tips stick out.
These are a 2.5 inlet, dual 3 outlet, total width is about 6.4 inches and length is 8.4 inches. Don't think you could fit anything bigger than that