Hi, I bought this exhaust.
http://www.evasivemotorsports.com/Merchant...Code=HS00HS1GTP

Please advise if I need to buy a test pipe as well.

I'm not too sure

 

Its not a necessity. More if you want one or not.

 

$ spent on test pipe worth the gain (if any)?

 

My opinion, yes. I think a test pipe is well worth the money. You will gain a few ponies, I like the sound of that invidia with the test pipe. It will make the exhaust louder, but it will help with the drone a little bit. So I say get one, but no you dont have to.

 

Thanks guys, decided, I will get one

 

Get one for sure its like 80 or less and has better flow than your stock cat, but make sure to get one with cel fix. Its going to be LOUD with your N1!!!

 

test pipe on my n1 sounded way to raspy

 

I'm using a 70mm berk test pipe with my invidia single and it sounds good. Its nice and loud, but the cel fix works perfect. Keep in mind though your 06 may not respond as well to the cel fix

 

Yes.

 

I have the same setup (for now) on my 2002. The TP helped with drone, but the car did get quite a bit louder at WOT. People have proved many times the gains are worth it.