HS - Aftermarket exhaust - Really necessary ?

I had a muffler delete for a while, and very happy with the sound and the cost, but besides the slight weight reduction and sound "improvement", have not noticed performance improvement.

Some TopTier National Level Autocrossers have changed to 2.5 " exhaust, but realistically is it worth? I have researched and basically what I found was that if we keep OEM downpipe there is no gain with a wider cat back.

Does it hurt to go wider?

Maybe the 8lbs. Titanium one ?

Thanks so much

Andres

No, the stock exhaust is surprisingly (disappointingly) efficient. It's one of the biggest restrictions for forced induction cars but unless you're changing it all (manifold on back) and going big turbo you're realistically just fine as it is for this car.

Well you’re going from 2.21” to 2.5”, not much bigger, but you still have that very small bottleneck with the stock cat. I just added an fswerks exhaust 1 month ago, it’s 5 pounds lighter than stock because it removes the resonator. I got it because it was cheap and quiet and still t304 ss. FSWerks claims +10 wheel torque at 2,800rpm. My butt dyno agrees. They also claim some high rpm hp gains which I don’t feel at least not with my e30 tune.

So in my personal experience it just exaggerates that stock turbo powerband with gobs of torque down low and pretty lame top end hp. Assuming you could control that extra torque with the right tires or an lsd I would imagine it could be useful for autocross. Again that could be slightly different with a good 93 tune because e30 tends to hit harder lower in the revs. I have to agree with @Business6 its not a must do until you go big turbo and do the cat at the same time.

The only advantage I see is being able to hear your RPM through a helmet. Very helpful in rallycross since there is some more shifting than in autocross.

^^^THIS is why I changed the factory system out for a CP-E Nexus, and not necessarily for auto/rallycross/open tracking, but even for street driving.
With my 70% hearing loss (as compared to what most on here have), and the factory system not even allowing me to tell the car was running being so silent, it kept me from burning up the factory clutch on take off.

I have seen theorized that a very lightweight exhaust such as aluminum tubing and no muffler might be an advantage, but I have my doubts... Having weight down low for a muffler or fuel or otherwise feels better to me, but I haven’t been able to prove a measurable advantage either way. I have the Tuned+ Lightweight SS version 2.5 system and think it’s very nicely made, but I don’t see a benefit with a 200TW tire that’s grip limited especially in acceleration on an already lightweight car. I see the lighter standard seats and no sunroof as a clear advantage though.

One of the reasons I specifically ordered mine the way I did.

That's more or less one of the main reasons why I modified my exhaust on all three of my Miatas. With the top down it's not that you can't hear anything but that you can hear everything and having ear plugs helped a lot but swapping mufflers, mid pipe, etc helped immensely when doing canyon runs and that sort. The other was to make the cars more "visible" to the rest of traffic around me. At speed the stock exhausts just got lost in the ocean of noise especially if there were other cars next to me on a multi-lane road

I only have the resonator removed on my FiST and I would love an exhaust. There's no justification for spending on it, especially right now, unless I hit some debris that damages it. Not that I'm hoping for that or anything...

I've actually thought about getting a cutout just so I can hear my engine through the helmet when on course- everywhere else, I kinda like the stealth of the stock exhaust.

Also the top tier autocrossers that run at nationals are looking for every single advantage they can get. Anything that can shave .1 off their posted time could be a winning run. Guys go to the absolute extreme to win classing while staying within the rules.

Bumping this, So for a big turbo is an exhaust necessary?