I was wondering what is the difference between the two? also does the DV add performance.

thanks


side note how can you tell what year it is like a 99 or 99.5

 

This will tell you the difference in model years.

http://ctny.audiworld.com/mark/a4/diff/

You should use a DV (Diverter Valve) also known as a BPV (By Pass Valve)

Using a BOV in a non tuned setup will make you run rich and fowl plugs/cat.

There is no preformance difference to a BOV/DV only the sound. A DV is quieter.

 

do you still get a cool sound out of the DV?

 

I know you are new, but use the search function next time. this is discussed 100 times a month


here is a helpfull post about DV and BOV

https://www.audiforums.com/m_14128/tm.htm