Nee Help Thrust Dual In Dual Out

[03DEENALY]

I have an 03 Yukon Denali with stock 3in dual in dual out exhaust pipes and muffler. I purchased a Thrush 2.25in dual in dual out performance muffler. When I took the muffler to get it installed the shop told me going from 3in to 2.25in would restruct the airflow and ultimately could stress the engine and cause problems. Is this true? Has anyone gone from 3" to 2.25"?

 

[livingez_123]

if you were running a ture set of duals 2.5 would be the smallest I would go on the 6.0
it won't flow as good as it should.