Hi.....again. I'd like to buy a Universal High Flow Cat for my 96 Monte but I have no idea the size to buy, here are my options.....which one is the right one?

2" inlet 2" outlet Universal Hi-Flow Catalytic Converter
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2.25" inlet 2.25" outlet Universal Hi-Flow Catalytic
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2.5" inlet 2.5" outlet Universal Hi-Flow Catalytic Converter
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3" inlet 3" outlet Universal Hi-Flow Catalytic Converter



These are pretty cheap in price, are they any good? Another site has them at $130.00, whats the difference?

Here are the 2 sites;

http://www.a-1parts.com/performance_store/display_table_superconverter.cfm?VENDOR=SUPER%20CO NVERTER

http://hoganperformance.com/Accessories.htm