Thanks for the replies everyone.
I purchased a brand new Japspeed K1 for my previous 350z I had back in 2009 and had problems with the midpipe catching heavily on the crossmember, pulling the flex's on the y-pipe badly. It was also catching on the rear anti-role bar and diff.
Safe to say I was really disapointed as I expected it to fit no problems, especially being a new unit.
I love the sound and price of the K1 but must admit im not a huge fan of the rear cans and with my previous dilema, am starting to think I should stay well clear.
In terms of loudness and value I think the Buddy Club & Invidia would be my best choice.
Ill keep looking