free-flow exhaust brands

So what's the difference between Moss's 'Big Bore' stainless system and Proper MG's Peco stainless free-flow system w/ header. I know the Moss system doesn't come w/ a header, but you could get the s/s system and a s/s free-flow header from Moss all for $480. Proper MG's system costs more than $550. What's the deal, Proper MG is a distributer and usually has much lower prices than Moss. These must be different design or diam. or something. Thanks for any thoughts.

I couldn't tell you the difference, but I would go with the stock Walker OEM exhaust, you will be very happy with it. Cost is about a $120 including a new downpipe off the manifold.

I went with the PECO but it is not stainless.
It sounds great(not too loud or noisy).
My original manifold was broken at the lower mount so I changed. The new PECO was on sale for less than $200 at the time. Good luck.