Performance Engine in GM 90's 1500's?

[Jonathan S]

So, I was talking with someone who said that some of the 90's and even earlier trucks were built at the factory with High Performance Engines and Camshafts instead of the standard stock 350's. He said he thought my 91 Suburban may have one because it has a 3 inch exhaust.

Was wondering if anyone knew if there is any truth to this and how I might go about verifying this about my vehicle. Thanks.