your setup is just a bit incomplete is all.. the owner should've replaced that front mani with the $140 plog before he pissed away $350 on those plug wires and airbox, the engine would've been much happier and safer.
if you got the modular pulley system on and your not comfortable with your set up , you can always buy bigger pulleys. they sell 3.5 and 3.6. it takes 5 minutes to change them.the smaller the pulley the more dangerous it is for your engine without the right supporting mods. if the 3.4 scares you, put a 3.6 on.
well you can invest in an aeroforce scan gauge ...$230
http://zzperformance.com/3800/gauge-...can-gauge.html
or
buy an obd2 bluetooth adapter and an android app that you can use with an android device , like a phone or a tablet.
you can get the adaptor for anywhere from $10 or more. then you buy the torque pro app for $5 and download it.
i got this one.
http://www.amazon.com/BAFX-Products-.../dp/B005NLQAHS
and i use an android tablet with it.
this is torque pro..
https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en
read this if you don't understand fully what knock retard is, or does to your engine
http://zzperformance.com/blog/about-knock-retard-kr/