Another exhaust question for the experts

[dave1123]

Well, this week I will be installing my Mopar/Borla cat back exhaust as well as a set of the SS shorty headers off a 2000 gts. My question is, the outlet from the headers is 2.5" and the inlet to the mufflers are 2.5"(reducer from 3") I can't seem to find the '98 and up mid section piece minus the cats for a reasonable price, so I'm going to have a muffler shop bend the right shape to mate the headers and mufflers. can I make this piece 3" also? the mufflers have a reducer that can be opened up to 3" and I was thinking about getting a coupler piece for the headers to make it 3" all the way back. what problems would this cause if any?

 

[95Viper]

There was a guy just last week on ebay who had cats for sale but the picture had the manifold connection back through the cat. I sent him an email and he said the sale was only for the cats $50 but he had the stuff you need too. Send me an email if you can't find it on ebay and I'll send you his email reply to me. You might get what you need cheap.

 

[dave1123]

I really want to know if I'll have back pressure issues putting 3" from the headers back. again, they are the stock 2000 ss shorty headers and I was planning on putting a 2.5" to 3" coupler at the header and then run 3" all the way back.

 

[95Viper]

You might want to do some searches because recently people posted test examples with different 3 inch setups and dyno'd the results. If you use the stock flex pipe after the headers, it isn't 3" so I'm not certain opening up to 3 after the flex pipe or opening the muffler to 3 will do anything. You either need to go 3" all the way out or not.

 

[dave1123]

I wasn't going to use the flex pipe, unless I can find it cheap. I have been in contact with people and I may still might go that route. Since I may have to have a piece made from the header back to the muffler, I just want to make that 3" all the way. this means putting a 2.5" to 3" coupler on the stock header connection. I was wondering if that is going to be ok.

 

[Marv S]

why not just use the cats from a 1998 or newer? Should bolt right up.

You can even have them opened up to the 3" if you wanted to.

 

[dave1123]

no cats for me. cooler for one, and I want to see what sort of HP difference I get with out them. I can alway put the high flows in later. others in our region have cut the cats out and like the increase of hp and cooler ride. figure I'll try it