I've got a '02 LQ4 in a OBS tahoe. For starters I can't run any kind of longtubes, schoenfeld's won't fit either because I'm 4x4. So I am running the stock 6L manifolds and then have 2.25" piping from each manifold into a DI/SO big case muffler. I fell this is way to small and want to get the most power out of it as I can. I have a TR224 and some other bolt ons and feel like my exhaust might be holding me back power wise.

So, I want to know if it is possible to run the NNBS y-pipes on the NBS stock manifolds. Are the NNBS y-pipes 3 bolt flange like the NBS? If not, I will get a NBS y-pipe.

Then my other question is will the 3.5" exhaust after the y-pipe fit on the NBS y-pipe? I know it's 3" v. 3.5" but could I bottleneck it to work out? Thanks for any help

 

I don't know what all is compatible but my 2010 had three bolt flanges.

 

Awesome thanks for the info. What size is that ypipe on the end?

 

Its 3.5"