IMO exhaust gasses are much colder by the time they reach the tips, that running 2" from the muffler to the tip won't have any effect on your car's performance.
No shortcuts here. Bryan had some hours into these tips getting them right. He said they were a real PITA to get that 2.5" pipe to fit in there and not loose the shape of the tip.
You paid them ... of course they complained it was a lot of work. LOL.
It looks like they cut it out, filed the hole into an oval, and squished the 2.5" pipe to fit (which is the only way really as the tip is 2" tall inside.
I was looking closer at the tips yesterday. I wonder what it would cost for metal faber to make a custom set to properly fit 2.5" and have the same look as stock? It would obviously be a little larger but I would think it would not be obvious. I would guess there are a dozen ways to go about it.