is this good for lb7?

[20chevy04]

http://cgi.ebay.com/ebaymotors/MBRP-01-05-GM-Duramax-6-6-Front-Down-Pipe-Flanged-4-SS-/380362424443?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A2004&hash=item588f5e007b
i want to buy a dp and keep finding differt ones i know this one is a straight 4'' but theres also this 3'' one?
http://cgi.ebay.com/ebaymotors/MBRP...ccessories&fits=Year:2004&hash=item2c5d0c0a47
which one is better?

 

[BlkMax]

see your other post.....