Greetings.

I'm trying to put an OE replacement Magnaflow cat between a DC 4-2-1 (D-Series) two piece and a GReddy SP exhaust. It bolts up to the exhaust just fine but the header side opening isn't big enough and the bolt holes aren't big enough either. I double checked that I had the right part number and I do. The stock cat fits just fine but it's clogged up and needs to be replaced. Thoughts, ideas, opinions, suggestions?

Car = '91 Si hatch w/Z6 swap, using A6 DC header.

 

I have the exact same exhaust setup. You'll just need to go to ace hardware and get some longer Grade-8 bolts with washers and nuts. It should run you around $10 to get the perfect length, and you re-use the stock springs. Dont forget to re-use the metal donut gasket on the end of the header ...it just fits into the bell-shaped flange on the cat.

 

That's what I thought.

Thank you, sir.