Custom catback

Is there anything that I should watch for or make sure of when getting a shop to make a custom cat back for me?

2.25 or maybe 2.5 inch piping, they use all the factory hangar points, and the system looks like its supposed to be there. the less welds the better

Update: Well, I got the bad boy installed. I bought a Bomz Evo R Spec on eBay, had the shop bend me some 2.25" aluminized pipe, and weld everything together. It sounds incredible! I can't believe a 1.8L engine can sound that deep. The muffler is the perfect size too. The guys at Halfmoon Valley Towing tucked it up under my car perfect. I just wanted to say how everything went so people could use this info for future use.