Since I am not able to find the answer for sure, magnaflow can not even tell me.. Has anyone used this muffler # 12259 center in with offset out) with the factory exhaust ? Does it go right in ? I realize it will need to be welded or clamped in. I also know that the factory pipe will have to be expanded on each side since this muffler is 3'' pipe on both sides. 08 silvy.. Thanks

 

Not an exact answer to your question but it may help. I used 12589, 3" 5x11x22 center/offset on my 02 Tahoe and it lined right up with the factory exhaust pipes. Being that the 12259 is a 5x8 case, the offset will be ~1.5" less and I am not sure if the 08 trucks use the same factory muffler as the older trucks/suvs.

 

I used part #11229 which is the same center/offset its just a 14" muffler and mine worked fine. so I think you will be good on that

 

Thanks BIGKID for the response. I am not sure if they changed either. I am trying to save a buddy some money, need a solid answer lol. I haven't messed with any NNBS stuff so it is new territory to me..

Muscle, did you have to have the factory pipes expanded, or use reducers and weld them onto the muffler ? Also you put this in the place of the stocker, so you kept all the orig piping ?

 

We put one on my brothers 2010 silvy and we needed to extend the pipes about 3-4 inches using the bigest 5"x11" case. It lines up well enough and cannot tell its been modified from the outside.

 

Does the 10's use the 2 3/4 factory exhaust also ??

 

Yup only the 6.2s got 3.5

 

Ok so did you all use reducers off the muffler to the oem pipes or or have the factory ones expanded. Just trying to get a idea. I can do whatever it takes, but again looking for a idea.

 

Yes I had the ends expanded to fit the 3" pipe by a local muffler shop but you can get reducers, its just a preference really. BTW glad to help