Header help needed please

[DaLostONE69]

OK so I'm re-doing my exhaust system from the header to the exhuast. But here's my problem, I trying to run a megan racing header with my hi flow cat that I had laying around. But i dont know the outlet size of the header and i cant find it any where. The inlet to the cat is 2.5 Is there a way to connet the two with welding them together?

Thanks in advance

 

[Blood_Shot]

measure the outlet of the collector on your header man

Im sure a shop can weld in an adapter or open up the end of your cat if need be