Was installing my FP red and the donut that FP provided is too big for my downpipe, and I 'thought' mine was a 3 inch invidia, (will have to check receipts) so I am running donutless

FP said I needed a 'true 3 inch dp'

I asked locally for a 'true 3 inch' dp and one person said that FP told him same thing,but none of them work and the guys at English Racing tried several others on his car, and none worked?

If I didnt pay for the o2 housing, id chuck it right now.

What are my options?

STM supposedly make a dp that fits the fp style 02 housing. Or you can cut and weld a new flange that fits.

seems to be the cheaper route

when i did mine, it came with the correct flange and donut so i cut the old one off my downpipe and welded the new one on.

It can work, I was mad at first but I used the donut that was in my exhaust since the FP it too big. I use my grinder to make inner bigger to be able to fit the ss housing. I created a mess shaving that donut. It was a tight fit but I was able to installed the ss housing with my new modified donut. No exhaust leak, so it can be done