I am eventually going to order the midpipe, cat, and resonator and want to get A/F and EGT(pyrometer) guages to go with them. Are there any in particular that you all recommend? I like the Defi, but they seem to be a bit expensive, I also saw some Greddy ones that look pretty good. I think the Greddy would be easier to hook up since they didnt require any extra control boxes or anything like that. What are your alls opinions on these two gauges.

get a wideband with a digital readout

Don't know that you need all that - you could get one of the OBDII-CAN scan tools here (http://www.rx8club.com/showthread.php?s=&threadid=25866), interface it to a laptop, and output the video to a dash mounted screen or even the Nav screen eventually. Gives you real time monitoring of all of the above AND many other things. Talk to CanZoomer about these - he know all about them, and as usual, has something up his sleeve... ;)