Do I need an FCD when running without an exhaust on a TII motor. How about with only a downpipe (if that even makes a difference)?
The setup is just a stock TII motor with a Walbro 255.
thanks

 

It depends on what series you have but either way you will probably see a bit higher boost. More importantly, you need to port the wastegate so that it won't creep. That will be your biggest problem espicially if you have an S4. And I would suggest running at least a downpipe so you don't start melting stuff in you engine bay due to the hot exhaust being dumped into the engine bay.