alright i've really been looking around. im trying to get an N75 i've looked on the internet for countless hours now and no one give a clear answer. what is the difference and which is better for what. and also when i emailed aptuning. they told me it wasn't recomended for my car. can someone tell me why it won't go on a 99 A4

 

go to 034motorsports.com find the n75s and read the description in each. im not alowed to post anymore.