[midnight23]

Originally Posted by ofuts

Hi, thanks for the reply.
Everyone suggested me to go with 3" catback if i was thinking about turbo FI, so i thoughed it effects the flow regardless of bottleneck of the system, and that free-flow effects the turbo performance greatly.
There will eventually be an outflow at one point, catback right now, but it can olso be overpipe or frontpipe, bottleneck will stay as downpipe. I guess a high-flow cat will make some difference for performance so thats the main reason i'm leaning on this, making it 3" would be better ofcourse. Not considering overpipe too much but read that curve of overpipe is only needed for JDM spec cars, so eliminating that curve can olso make a difference.
So my question is, am i thinking wrong, is it not worthed? I mean if there will be only around 5-8whp differnce after turbo, it is for sure not worthed the money, time and potential problems, which are more difficult to solve here in China.

3" front pipe catback will get best flow, leave overpipe 2.5" for less issues