Modding intake and/or exhaust components is popular because they change the car's character, look, sound, and/or response. But I've learned those mods can cause my cars to run sub-optimally without a proper tune. Because non-nominal turbulent airflow sensed by the MAF throws the ECU into a reactive loop trying to modulate air/fuel ratios back towards nominal throttle mapping.

The owner below comments on this without making too much of a fuss about it. Her comment made me realized that's precisely what keeps me from going down the rabbit hole of aftermarket BPUs. I'd trust the less popular, milder sounding Borla GM accessory exhaust over the aftermarket Borla models because I suspect it's matched to the factory tune. What converted me into this mindset is my Mustang with Roush CAI/Borla catback. When I finally added Roush's tune, it sounded more refined and ran smoother with more power. And my Edelbrock Supercharged BRZ with an aftermarket GReddy exhaust. When I swapped the exhaust back to stock (Edelbrock's baseline configuration for its supercharger was tuned with the stock exhaust), it pulled harder and ran smoother. Both those tunes were smog legal. I don't know of any C8 tunes that are smog legal (yet) which limits me to the GM Borla exhaust being matched to the stock tune. But I prefer to keep my NPP exhaust due to its loudness being close enough coupled with other tradeoffs.

Curious if anyone has noticed this phenomenon like this owner has. She talks about fixing it with HP Tuners which would "definitely be a gamechanger." This link should jump straight to her comment at 11:33:

 

Not to discredit/dismiss the "opinion" of this ONE owner but I have more trust/confidence in this guy:

 

I'd put more weight in that if it were a 3rd party conducting a rigorous engineering evaluation instead of the company selling it. His engineering speak is part of the reason I chose Borla ATAK for my Mustang. Despite his amazing marketing, it's still mass produced with profit at top of mind. At a certain RPM (around ~4k), my ATAK with its patented sound chamber would sound raspy and restricted. Made me wonder about having gone with the Stinger (aka Type S) which has more straight piping instead of that sound manipulator. And my MR-S had a Borla that eventually rattled. Not the same caliber as, perhaps, Akrapovic or Novitec exhausts. It's the difference between getting a solid product out that's still attainable to the masses vs obsessively pursuing perfection with less restrictions on cost.

 

Also that "one" owner doesn't mention Borla at all. Whatever Borla guy says in his video is irrelevant to her build because she's not running a Borla exhaust. Which tells me you probably didn't even listen to her opinion. Only I mentioned Borla to use as an example in my point about the factory tune and tuning in general.

 

in researching which exhaust to choose you will see many many brands and installations on forums with the owners asking how to get rid of the codes it throws and problems they are having (with TOP brands)

after doing my research I opted for the Paragon Touring system, no codes, no problems nice sound............my 2 cents, there are systems available that do not need tunes and do not cause problems

 

Ironically the owner in the video wanting a tune also has a Paragon exhaust.

My concern isn't so much about throwing codes or a CEL. I've never had that problem on any aftermarket exhaust without a tune. But they do alter airflow at each stroke of the exhaust valves. Probably due to their inherently different shape altering dynamic back pressure. So I would notice maybe a touch less torque down low but then a surge of more power at higher RPMs. This is even more pronounced with intakes without a tune.

 

I installed the Eventuri intake and (hopefully next weekend) the pDR/Lingenfelter Intake Manifold... bolt-ons, no tune, no CEL, claimed ~40 whp between the two.

 

I remember a member here years ago with an earlier computerized version Vette complain that he'd taken his previously excellent $70K sports car, spent $15K more on performance enhancements only to end up with a $90K "brick." Truly effective bolt-ons, at least that do something perceptible beyond make noise, are limited today.

 

I'm sure no expert, but it would seem to me that if it doesn't require a tune it isn't doing much.