bowen on your muffler let me know how you go...I been looking at a whole magna flow kit ...here is some other stuff I found on all par people taking about airflow adjustments
Steve Porter was happy with his K&N filter, saying:
The filter worked out great. It's a little throatier, and if you're doing say 40-50 and ya punch it, she really kicks in. I noticed a better shift, better throttle response and lots o' tire smoke (with traction control off).
Douglas Miske adds:
Owners with 3.5L engines can find a few free horsepower by removing the airflow restrictor found in the hose that runs from the air filter to the intake manifold. Simply disconnect the hose at the air filter end, reach in, and pull out the cone-shaped restrictor. The engine will sound throatier, and performance will improve above 4,200 rpm (when you're using the higher air flow short intake runners). Chrysler installed the restrictor mostly for sound quality, according to two dealers I asked.
Oliver Liu wrote:
I removed the airbox restictor, waited 3 days, installed a K&N air filter, waited 5 days, and then replaced the muffler (the large rectangular thing under the rear seats) with straight pipe today.
It sounds REALLY aggressive. The 3.3l engines have the muffler as well, but the 3.5l engine have a resonator after this (where the dual exhaust tips are). This is the only thing I have between the cat and the tailpipe now.
The airbox restrictor did almost nothing, the K&N was a subtle but nice change, apparent under hard accelleration. The exhaust mod is borderline obnoxious. NO CHECK ENGINE LIGHT comes on, this is a popular rumor.
Mark A. Chastain wrote:
I own a 1995 Intrepid, 3.5 Liter. I have read the articles here and followed them. The flow restrictor is gone, and the resonator has been replaced with a glass pack of the same size with two 2.5ID outlets so that it looks similar to stock. The sound is definitely better, and the improvement in response is noticeable especially while on the interstate.
I think everyone is missing an important issue. The rubber duct between the airbox and the fenderwell. If you haven't looked at it, you should. I estimate that the rectangular inner measurements are less than 3/4 inch high, and less than 5" long. I cut out that section, retained the ends and connected them with some cheap universal airduct purchased at the local car parts store. This opened the duct to a minimum of 2" high and 6" long. I made the other mods at the same time, so I can't say if this alone improved performance, but it seems to me that that duct is definitely restricting flow.