Gibson Dual in/single out 4.0 SOHC

[entinnovations]

I'm planning on buying a Gibson muffler and having a muffler shop custom make the exhaust pipe. Problem is, I have a dual in/single out factory muffler. On the gibsonperformance website they have all the various mufflers available but the only one I see that has dual in/single out has a 2.25in dual inlet(which is fine) but a 3in single outlet(which isn't fine). Has anyone purchased just the muffler and had a shop install it? Should I just get a 2.25in single in/single out and have the shop use a Y-pipe? Any opinions on this would be great. Thanks

Justin
99 4DR 2WD 4.0 SOHC

 

[EBInterceptor]

My Flowmaster is dual 2.25" in / single 3" out. I reduced it to 2 1/2" pipe and ran that back from the muffler.

 

[entinnovations]

Ok, that sounds like a good route to take. The dual outlets coming out of our SOHC cats are 2.25in right? I just ordered a KKM, could you tell a difference in the sound of the engine when you installed your KKM?

 

[EBInterceptor]

Yeah, you'll want the 2.25" inlets. The sound from the KKM is very noticable, gives it a nice throaty sound just like it says on their website. I have some pictures of my KKM on my cardomain page in my signature if you care to see. Pictures are a couple months old so I don't have any exhaust pictures yet or other mods.

 

[entinnovations]

How do you get the stock air box out? I was looking at mine today and couldn't see any bolts that hold it on except for some that from the fender to the side of it, but they don't look accessible?

 

[Rx4phun]

EB is your flowmaster just a straight 50 series or is it delta flow and tell me about it a bit. Do you like it? Are you happy you went down to a 2.5" pipe or do you think it would have been ok at 3". and do you know the muffler number b/c I was having a hard time finding a dual in/ single out. Other wise i was thinking about going with a 40 series and just gettin a Y-pipe before the muffler

 

[X24]

How do you get the stock air box out? I was looking at mine today and couldn't see any bolts that hold it on except for some that from the fender to the side of it, but they don't look accessible?

Unbolt the 4 MAF bolts from the top of the airbox. Undo the 2 clips holding the top of the box on and remove the top and the filter. The bottom of the box it held on by 4 pop in things. Just pull up on the side farthest from the fender. Once that side comes up the other two will pop out from the side of the fender by pulling toward the engine.

 

[EBInterceptor]

After you disconnect everything like X24 said, you can reach down the side and feel a place at the bottom of the airbox..I took a screw driver and put it between the bottom of the airbox and the plate that it's mounted to and pryed it up. Worked from the center of the engine towards the outside and pulled it from the sidewall last. It has big rubber grommets that it's mounted into, takes a little bit of effort but then will just pop right out.

I'm happy that I went with the 2.5" pipe. 3" pipe is really too big for our engines. I have the 50 SUV performance with dual 2.25" in/3" out and the part number is 524553. Got it from Summitracing.com for $98 shipped.