I got a 98 jdm itr 4-1 header that i got rewelded at the runners. The problem is that the welds went through so when you look at the inside of the runners, you see little droops of weld that went through. I heard of people porting out their header a little more then stock. I was wondering how much i would have to port it out, Also am i albe to just use a high powered dremel tool to port it out myself. thanks

 

use a dremel and grind away the welds. dont take any material away from the tubes.... it'll weakin it and make it prone to cracking when it goes through heat cycles.

 

Taking 1mm off of the flange area will help create a lip at the head and prevent reversion.