If its not a kit designed for the v6's Y pipe (such as takeoffs) then yes, youre going to have to cut the Y pipe and either get 1) custom fabricated H pip from that cut tot he takeoffs, or B) the pacesetter adapter. I recommend the pacesetter adapter... it's what Ive got on my car and I did all the installation myself. It comes with very clear instructions, and all parts needed. You've got a 99 so the tailpipe hangers will work just fine.
I like toys