stuffinder

I know most of us us orig or high quality OEM filters but I often see people changing to K & N etc. Although old this test seems to have been executed well. FYI

ISO 5011 Duramax Air Filter Test Report

A6Gary

Great report. That test report is a sound basis to dispel the "claims" by aftermarket suppliers that their air filters improve performance, filter better, etc., etc. K&N filters use a oil film in the filter media to capture dirt/dust. But, as this test report illustrates, that configuration leads to reduced filtration ability once the oil film captures the initial dirt particles, and then becomes ineffective. I have only used OEM-supplier filters in my German vehicles and never had a problem with in the intake system or scoring the cylinders. And the same applies to oil filters, e.g., Fram vs. OEM.

beep-beep

Love it.
Now if only someone can compare performance 20" rims to 16" rims and put that question to the rest.

twopedalwarrior

On a mazdaspeed I own, going from stock 15" rims to 17" Racing Hart rims cost me 4whp on the dyno

stuffinder

As to rim size, do you relate that WHP loss to gearing change or weight gain?
I've run 16,17,18 & 19 in wheels on my 3 C6 Avants! Since I'm in the Central NY and primarily secondary roads I find 17 in. to be my favorite. Less cost for tires & more cushioning for pothole protection! I've run Nokian Zline's (superb High Performance summer tire) on the '08 in both 245/45x17 & 255/35x19 and found 19's give marginal increase in high speed handling with slightly reduced comfort & Greatly increased cost of tires. Marginal decrease in fuel mileage as well with wider tire! YMMV

twopedalwarrior

Old post but just saw it. It is due to weight gain of the rims. The racing hart rims are rather heavy, and out weigh the stock 15" rather easily