I'm not sure if I can help you, on my my 03 the O2 sensors screwed into the xpipe exactly were they were on the stock h-pipe. I'd call SLP tomorrow and ask their advice.
Help quickly, please!
I just did my x-pipe. Don't bother jacking the whole car up, just jack the front as high as it will go and use 2 jackstands. It'll be tight but manageable.
At a track in Mexico, I got the needle past 150 in 5th w/ my 4.10s. Not sure how fast I was going 'cause of the error in the speedo. Suprisingly, the car was smooth.
It's amazing that you can hear that distinction. They are both straight through pipes. Anyways, I have the LM and I've heard the Packs and they are very similar. You can't go wrong w/ either one.
I can't actually answer your question but why don't you just give steeda a call. Other than that, look at Maximum Motosports. Again, call them and ask the same question. Good Luck.