:lol: why the need to modify your exhaust
Its around 3-4mm i had to bend it and I'm running a 3" mandrel front pipe. if you are using the the high position factory cat every car I know that has had one fitted, including HKS 2 3/4 frt pipe all have this clearance issue, Maybe if your making a custom bro exhaust you will hopefully remember to have the H brace fitted when exhaust is being made as there is sweet F'all room you have even useing a factory EIII frt pipe.
My factory EII (smaller diameter than eIII) will clear it with no issues
I'll find some pics and illustrate it for you.