Custom Exhaust Questions

Sorry to start a new thread, but needed to ask some pretty specific questions, and couldn't really find another thread that was appropriate to ask.

Ok, so I am thinking about doing a custom exhaust, more or less. First I'll thorw out a couple of my ideas, and then the question(s) I have.

I typically don't run Flowmaster on my previous trucks, and have in the past elected for Magnaflow, Borla, etc. That being said after watching as many sound clips, youtube videos, etc. on few people that have changed out their exhaust on the 3rd gen/3.5L, I have to say the video of the guy in Hawaii that put on the Flowmaster 40 Series Delta, has impressed me the most. Here's the videos for reference:
https://www.youtube.com/watch?v=4l9Twi1Yehs

https://www.youtube.com/watch?v=pDelJ1pxRXo

Now I understand that a new downpipe/muffler system isn't going to give me any real world gains, and I'll never get a V6 to sound like a V8, but that being said I would like a little beefier sound than the stock exhaust.

I don't want to go with a dual exhaust however, just a single in / single out.
I'm also not really interested in complete weld on kits, such as the Magnaflow... I like my parts welded together, not held together by u-bolts.

I have measured the stock pipes before and after the y-pipe/down pipe connection, and both appear to be 2.5".
I was thinking it would be nice to do a 3" pipe after the flange connection, and run 3" from the flange to the muffler, and then 3" out to the tip (like the Magnaflow system uses)... It would be nice to have a bit more flow before and after the muffler.

All that being said, my issue die to my lack of experience is, what would be the best course of action for the flange that connects the Y-pipe to the down pipe system? I would effectively be going from 2.5" to 3".

Is it as simple as just buying a aftermarket 3" flange for the down side, and a 3" flange gasket, and bolting them up?
Something like this: http://www.himni-racing.com/turbo-f...pipe-tube-ss?zenid=1nhir5i7ckriv8d5jf2mcs5ct2

Do I need some kind of flange adapter to put between the two flanges?
Like this:


Should I just leave the factory flanges on, and add reverse a reducer to go from 2.5" to 3" after the flange?
Like this: http://www.himni-racing.com/turbo-f...inless-steel?zenid=1nhir5i7ckriv8d5jf2mcs5ct2

Or, should I do like my welding guy suggest, just cut both flanges off and weld pipe to pipe? Guess I have to add the above transition piece between the two pipes as well.

What I'm basically getting at, is I want to more or less do the Magnaflow system, but with a Flowmaster muffler, and all welded.

Thanks for any input or suggestions you may have. Sorry for the long post, just tying to be as detailed as possible.

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