stock OBDI gsr - 50 trim t04 -Hondata S200 w/ boost
Im running a 3" downpipe and want to go 3" all the way back.

From the downpipe -> ? ? ? ?--- 3" piping-> 3" in/ out resonator-> 3" in/out turbo muffler

^^^
What should I use after the DP?
A 3" in/out cat? 3" test pipe?
Will the O2 sensor need to be plugged in?

 

if you can get away with running no cat go for it, just straight pipe it to the resonator and muffler. if your local laws are strict on cats, run the cat and a muffler and ditch the resonator

 

But withoug a cat he will contributing that much more to globull climate change... just make sure you buy the appropriate carbon credits!

 

No cat, No resonator. Just a nice muffler. I run a straight 3inch with a magnaflow muffler, and it is awesome.

 

Magnaflow does sound really good.

I'm running 3in out to a Magnflow muffler, but I have a 3in/3out cat and a resonator. Make it 3in, a 3in cat and 3 all the way back and you'll be fine.

 

Im thinking 3 inch in/out vibrant street power stealth.. I like the flat black sleeper look.

 

Cat really isn't nessecary, unless you have pollution laws. I like how my muffler comes out on an angle. Main reason for resriction. I have my exhaust running straight back, down the center of the car, and then a 45 bend to kick it out the back. Secondly, because everyone has their's coming out straight. I like to be different.

 

You're not , sorry. The angle thing is a fad that's came and gone. Sorry.

OP - I flat blacked my Manaflow and front-mout. Sleeper FTW.

 

It's common sence, more bends, worse the flow is. I have a 90 to bring the pipe back, then a 45 to kick it out, versus the 3 - 90 bends, if you have it sticking straight out in the stock location. I'm sure it's not a huge difference, but I know it does a little bit of a difference. Plus, it's easier, and looks better, in my opinion.

 

Right. Darkness FTW. I like the stock look and the look on people's faces when they under-estimate you .