About the 3" exhaust I got

[daltah]

I got a tsudo cat back on ebay that is is 3" and my question is, Does all 3" catbacks have a 2.25 inch opening where it bolts to the cat? Its not just the flange but the piping right after the flange I measure it and its 2.25 but the inside of the piping on the other 2 pieces to my exhaust are full 3".

 

[4G63Boosted]

A lot of them do. They do this so it can be bolted up to the stock catalytic converter. If the flange opening was 3 inches at the cat, it would never seal and you would have a huge exhaust leak. I have the Tsudo Fireball, and mine is the same way. Once I get the rest of my 3" exhaust, I will cut that small section out, and weld in a full 3" piece with a new flange.

 

[DGajre777]

My Apexi N1 is 3" and had a 2" long adapter to bolt on to the stock cat.

 

[GreddyGst]

My Apexi N1 is 3" and had a 2" long adapter to bolt on to the stock cat.

I have a Espelir exhaust and I too got a pipe reducer to fit my stock cat (assuming I was going to bolt it to a stock cat) But because I bought a 3" test pipe I didn't use and I connected both pipes together.

I don't have experience with Ebay exhaust and only you can tell if it 'really' opens 3" inside the pipe. I think is one of those fake exhaust you hear about OR it goes to 2.25 and opens to 3" but where? Where does the 3" start? can you tell? Does the pipe increase size?.. only you can tell and if it doesn't get your money back and buy a real 3".
Most exhausts that are real 3" give you an adapter like they did to me and DGajre unless they were meant to be 2.25 like the old Greddy Evo exhausts and just are meant to fit your cat from the start.
Good luck with this.

 

[4G63Boosted]

The 2.25" section is only about 2 or 2.5" long before it opens up to a full 3".

 

[DGajre777]

The 2.25" section is only about 2 or 2.5" long before it opens up to a full 3".

Buy a 3" flange, take it to a shop and have them weld one on where it opens to a full 3".
http://www.roadraceengineering.com/flangesandgaskets.htm

I think instead of giving you an adapter, they welded the 2 pipes together.

 

[DiamondStarM]

Yea the Tsudo necks down to match the stock cat, your best bet it to have a new flange with a little section of pipe welded in or you can port match the flange at an angle so at least the exhaust doent just hit the lip of that hard edge, assuming you have a 3" downpipe/cat. Of course then you would have the small section of pipe but at least it would have a smooth transition. Id cut and weld though, personally.

 

[MNGSX]

Just cut off both flanges and run a section of 3" pipe with slip fits and band clamps..

 

[4G63Boosted]

I already plan on removing the neck down and welding in a full 3" piece with a new flange to meet up to my Authority dp when I get it.