CAI for 03 V6

Hi, I have an 03 V6 and was wondering if any knows what the differences are between cheap 60$ CAI sets and the expensive 300$ CAI sets. Will puting one on the 03 V6 have much of an effect. Also, would replacing the stock muffler with a Flowmaster 40 Series delta add a great amount of mean muscle power or do I have to put duals on or a whole new exhaust system? I'm tight for money now, which is why I'd like to know if these options will hold me over until I get enough dough to roll with. Thanks.