Okay, we can get back on topic rather than arguing about headers.. there are arguments both ways and too many types of headers to compare accurately by what people say.
As far as the install goes, it is pretty easy. The only part not mentioned is removing the straw that is part of the PCV system. You will know what it is when you get there. I had do use my Dremel to remove the tabs that held it in place - nothing major.
To do the install, I first unbolted the injectors. Then I unbolted the rest of it. I was able to pull the Upper plenum out completely so I could actually get the HV3 in. It is a very snug fit. After that make sure you put all the bolts back in and tighten them to their torque specifications.
If I were you, I'd save my money and do the HV3/Downpipe at the same time. You will really notice a difference, especially with a custom tune. It will be worth the wait, trust me. I have a N/A monte SS with a Custom CAI (I made the box out of plexi, it's similar to ZZP's) with a 9'' K&N filter, 2.5" DP (Plenty for a N/A setup), HV3, Custom tune. I also have a Ported throttle body that is sitting on my desk. Car is definitely peppier, especially in the high rpms. It pulls pretty hard on the freeway :th_thumbsup-wink:
Hope this helps!