The bolt holes on my header and test pipe don't line up. Should I....

1. Drill new holes?
2. Elongate the existing holes?

The flange is 1/2" thick by the way! I have a hand drill and some drill bits.



How would you go about cutting into 1/2" thick steel?

 

local muffler shop will get it done for cheap

 

Those holes look way too close to the pipe itself. Make sure there is enough room for the washer/nut or bolt head before you drill.

 

Cut the old flange, get a different one welded on or clamp it on.

 

I ended up drilling two 3/8" holes and that wasn't that hard at all. I haven't installed the header and test pipe yet because the donut for the header is too big for the test pipe, which was advertised to be 2.5" also. So I'm trying to grind off material on the donut gasket.