hello everyone. I am about to install 2 forty series flowmaster mufflers on my pickup, and the mufflers have a 3 inch inlet and outlet, but my current setup uses a 3 1/2 inch pipe, could i just down size my pipe with an adapter? Or would that cause flow troubles? by the way this is my 2002 CHevy with a 6.0 Liter vortec engine. Thanks to all!