Fry1nDutchman

im getting a custom 3in exhaust system on my b5 a4 in 2 weeks and want to know what are the pros and cons of both the test pipe and high flow cat. i know you CANT pass inspection with the test pipe but CAN pass with the highflow cat. Also is there a horse power or volume difference between the two? any other info would be great thanks

HBAudi

Perhaps your questions are best directed to the person installing the new exhaust system.

With any exhaust system, many factors determine the system's efficiency such as the inside diameter of the pipes; dual vs. dual into one; number of mandrel bends and their angles; 'tuned' vs. 'non-tuned' headers/manifolds; location and size of the resonators and location and size of the muffler. In addition, is the system being designed and built for a racing or street application, is the engine normally aspirated or turbo/supercharged and is the system designed to increase torque or horsepower?

Fry1nDutchman

the car is a 1.8t b5 a4 5speed.. The system would be used for street applications, and main purpose would be horsepower and tourqe. I didnt plan on using resonators and would be using 3in down and mid pipe to a "borla turbo" muffler.. i wouldnt want to touch my headers untill i get my k04 or gt28.. ill have to ask the guys at the shop what they think.. thanks!

RallyVermont

Been there done that, prefer my high flow CAT. The gains are really not discernible between the two if you get a quality highflow CAT. You'll gain more low end hp with the CAT and more high end with the TP.

I'd go with a good CAT over a TP.

Fry1nDutchman

thanks man! i was looking into the mangnaflow highflow cat is it any good?

600whpA4

For a K03/K04/GT28 that is going to be used mainly for the street I would suggest going with a high flow cat.

O34 offers a 3" high flow cat that is a stock cat replacement.

http://www.034motorsport.com/engine-...t-p-18175.html

RallyVermont

Don't know enough about magnaflow.. I'd suggest what 600whpA4 linked to. A great replacement. You'll have better flow than Stock, NO CEL.