I over tightened it and now there are barely any threads left. Where can I get a replacement?

 

try Mishimoto.
Here is a link to their distributors page.
MISHIMOTO distributors

 

Or Try Evasivemotorsport.com

Speedelement?

Groupe 5?

 

mishimoto ?

 

I didn't see anything on Mishimoto's site. Do you think Home Depot or Lowes or maybe even Ace would have something sort of the same that I could use?

 

You might try finding a bolt with the same length and thread pitch. Just take it to lowes/home depot and match it up in the bolt bins. Prolly save you time/money/shipping.

 

is it a straight plug or a tapered plug
if straight probably metric
if taped probably British tapered pipe
do not mix British tapered pipe and national tapered pipe
they look similar and can be hard to tell apart unless you have a set of gauges and a small microscope
probably best to call a Mishimoto dealer

 

call dealer