BA XR6 Turbo catback exhaust lean/rich or fine without tune?

[Bawwxay]

Evening everyone, I recently had a question that despite my research can’t find a definitive answer online and was wondering if the infinite wisdom of these forums might lend an insight into it. 
My xr6 turbo has been tuned a few years ago and since then I have deleted the factory middle muffler (dual in/dual out) with dual straight pipes, keeping the rear muffler in place and have no issues whatsoever with air/fuel ratio. 
I now am curious about whether I add a straight through muffler (dual in/dual out) at the rear instead of the chambered factory one, whether this will cause any leaning out without a retune? 
it still has factory dump/cat. 
opinions?

[bupalooga]

From memory, the factory cat and dump are the restrictions, so you can basically do whatever you want with the rest of the exhaust without needing a tune.

[k31th]

correct ^^

[Bawwxay]

That’s what I have always been told, as long as it’s after the cat, then there “shouldn’t” be a difference in the computer trying to remap small parameters for more exhaust air flow and ending up leaning out.
 would rather be 100% certain before spending $$ on a tailpipe section and then more $$ on a tune. 🤪

[Puffwagon]

Facts: The fuelling is in open loop at wot so any airflow increases or added efficiencies will lean it out slightly. Nearly all partial throttle driving will be handled by the O2 sensor aka closed loop, so won't change as far as the final afr is concerned.

 

Opinion: I wouldn't be worried about updating the tune for a catback. I also wouldn't bother with a catback unless I was getting it tuned. It'll be a whole lot of money for mostly noise.

[Bawwxay]

I appreciate You adding Your opinion, this whole thought train came about by wanting to add a different note to the vehicle (ie more loud) without drone or affecting performance at all (yeah I know, stupid really)

I have an Ultrex 4” turbo back exhaust, 5 inch hi flow cat and 4” single tip, sitting in the box still, until I do a few other things before a tune, as it wasn’t a daily driver until now, and driving it everyday I notice I want more loud 🤣 

can pick up a rear straight through muffler section for $300 and am deliberating. 
the next thought is as it’s a sleeper-ish build, can I stand the look of dual 2.5” out tailpipes with no tips. 
opinions on that look please? 
 

I think I prefer the factory dual into one oval chrome tip, or the big ass 4” Ultrex outlet. 
I have seen a few XR8’s and a couple of Turbo’s with twin outlets and I’m still not sold on the look.

[Puffwagon]

Man if that's what you wanna do then go for it. Noise ain't my thing but nothing wrong with it if that's what you want.

 

Couldn't be too hard to find some tips that can be tacked on afterwards.

[Bawwxay]

You know what, at the moment the current note sounds more “refined” than “obnoxiously loud” I guess I’ve just been seeing too many cackle tuned vehicles around and thinking that it would be “cool” and not annoying on a daily basis. 
Thanks for the refresh Puff! 🙏

what tailpipes do You prefer on Your fords? 

Edited 11/06/23 10:22 AM by Bawwxay
Added a question

[Puffwagon]

I like the turned down look with the big single pipes. For twin exit I like the staggered chrome look. Haha pretty simple I know but it works for me.

[Bawwxay]

Completely agree! 
the ultrex turned down one was why I got it, plus 4” haha 

I’m considering the bosozoku/skid car look of twin 3” straight pipes angled about 6” from the bumper (not straight up in the air, just straight out) 

too out there? Lol