LS4 Performance - Muffler help needed

I had a pair of knock-off Flowmaster's installed last fall, and they sound horrible inside the car. It's way too loud. It's so bad you can barely talk on the phone even at 30-40mph. I replaced my factory mufflers because there was a hole on the top of one. I could tell something was wrong because they started getting really loud. After getting the new ones put on, it sounded a little better, but it's still way too loud inside the car. I'm guessing it's because I bought cheap mufflers. Is there another possibility? I went with the knock-offs because they were only $60 for a pair on eBay. Here's a link for the type I got - LINK HERE (http://www.ebay.com/itm/PAIR-2-25-2-CHAMBER-40-SERIES-STYLE-RACE-MUFFLERS-2-1-4-MUSTANG-HIGH-FLOW-/150787368533?pt=Motors_Car_Truck_Parts_Accessories&hash=item231ba0a655&vxp=mtr)

Can someone give me a suggestion on a possible replacement that won't cost too much?

You get what you pay for.

You get what you pay for.

^Love that quote

But yeah, you can probably go to a shop and have some Magnaflows put on for $200-$300 depending on the muffler you pick and labor costs.

X2 on magnaflow if you don't want the car too loud. Or a flowmaster 50 or 60 series. My super 44's were $75 each shipped

Would you buy your girlfriend fake diamonds because they were half price? Then why would you do that to your car lol. My flows were 135 a pair shipped. To have them welded shouldn't cost more then 100 bucks

I had both mufflers installed, as well as the some tips (http://www.ansaautomotive.com/wp-content/uploads/2011/05/SV78193-e1308170002725.jpg) I bought, for $120. Does anyone have a suggestion for where to find good deals on mufflers online? I'm sure it will be cheaper than buying them from the local muffler shop. If I could keep the price of 2 more new mufflers under $200 that would help a lot, because I still have to pay for installation. Thanks for everyone's replies. Any help is greatly appreciated.