vijen6,
Let me start by saying my install was on a 2000 2.7 with the 5-speed manual. I'm not sure what year, engine and transmission you have so there may be some differences.
Does your NHP muffler look exactly like mine in the attached thread pics? I know there was an earlier version of the muffler, and then a subsequent version with added bracing above and below the muffler tip area. You can see the short horizontal braces in my pics.
I honestly don't remember much about installing the muffler but I don't think I had any issues or concerns about the mounting location and didn't experience any issues thereafter. I also didn't remember much about the mid-pipe installation but have since looked at some of my old pics and see what you are referring to regarding the mid-pipe flange mounting points (or lack of them). I didn't add any additional supports and didn't have any issues.
I didn't experience the lower RPM vibration you describe, but also didn't have any vibrations by shaking the system by hand like you describe. So you may be correct in your diagnosis and the ability to shake the system by hand and cause vibrations is the cause of your lower RPM vibration.
So I didn't experience any annoying vibrations or droning (at least none detectable by my untrained ear) in my car after the NHP install. For some context, when I installed my NHP system I removed a Stebro Sport muffler that droned like crazy. So this was a huge improvement for me. If you are coming off of an OE set-up your perspective is probably different. I also had been running without the snorkel for years. I did add a BMC drop-in air filter when I installed the NHP system.
I don't remember any burning smells either. Could it be from penetrants you used on bolts when removing the old system? I was concerned about the new headers contacting lines but my research made me think it was a non-issue on my model, year, engine and transmission, and that was the case. I didn't have to move or tie anything up during my install and never had any issues. Depending on your car specifics that may not be the case. Obviously you are right to be concerned and cautious until you get this figured out.
I hope others with more to add will chime in as I feel like I haven't had anything helpful to contribute. Keep us up-to-date as you progress.
ddb
|