Originally Posted by Money2536

iPE is super shady. They have ruined it for a lot of people by making fake profiles and sharing douchey videos on here and 6 speed. I think I know why they don't ever have any tests of their exhaust. The people that buy them don't care and it most likely loses power. If I had bought one, I certainly would have tested it. But... like other have stated, it's not like the car needs more power, but I'd rather not spend $5000 and lose a bunch. I said earlier, the resources they now have will hopefully move them to invest in real engineering in Taiwan.

Originally Posted by Money2536

Alright...I guess I'll chime in here as I had 12 different variants of exhausts on my 991.1 GT3. When I first got my car, the iPE was the only option outside of two bypasses, GMG and Sharkwerks. I came from a 991.1 C2S that didn't have to goofy valve transition that the GT3 has. I wanted to press the button and have the valves open. Press it again and have them close. Or...even better, just get rid of the valves all together. After spending a little time discussing iPE and then seeing and inspecting it in person, I came to the conclusion that it is not good. FI, Armytrix, iPE are all in the same marketing company category (aka junk). In the 3 1/2 years the thing has been out, I've yet to see a single dyno plot outside of their original site showing a 40whp loss in the lower RPM range. If you gave me one, I wouldn't take it. Zero testing, all marketing. YouTube is a powerful thing. We can only hope the success of these brands will lead to make some legitimate products in the future.

Akra is a work of art, but doesn't do much. The full Akra Evolution system is a really expensive, $11,000, copy of the stock exhaust, so that doesn't make much sense to me. I've spent about 5 hours on backroads behind the wheel of and Akra equipped car. No power, slightly lighter weight, very slight difference in sound, and a crap load of money is not for me. You could do the race version deleting the side mufflers, but that drones a crap load.

The bypasses, Sharkwerks, RSS, GMG, etc. with or without the valves connected are a solid option. ***You must remember that pressing the valve button doesn't do much other than closing the valves at idle.*** On or off it operates identically once you press the gas. That's the advantage of iPE with the remote option. You have the ability to open the valves and leave them open. Other exhausts don't have that option. Stock, with the button on, the valves close again and then reopen depending on throttle around 3700 RPMs.

I tested a bunch of iterations with FVD Brombacher. Their manufacturer M&M made 3 different iterations to try, but they all failed. They really didn't test anything, they just made it based on their 997 experience. I had eventually settle on the GMG with the valves disconnected. Many thought the car would lose low end power without the valves. I tested and retested on the dyno and proved the valves actually caused us to lose low end power. I came to the conclusion the valves are simply there for drone reduction.

So onto the most viable solution in my book, Dundon. I had a 2 hour conversation with Charles Dundon (he's a mad scientist) that I didn't want to have. I was on my 11th exhaust variant at that point and had finally settled on GMG bypass. I took a flyer on the very expensive option due to one simple fact. They had done hundreds (yes...hundreds) of dyno runs and massive calculating/testing that no one else had done and probably still hasn't. Dundon uses T321 stainless instead of much cheaper T304. Race headers are catless, so I wouldn't do that if I lived in an emissions testing state, but I made +55whp without tune and a little over +70whp with it. The plots they use are a bit conservative in comparison to my findings. My 2014 E series engine equipped car walked away from a '16 F series GT3RS. Due to their O2 sensor extension design, you don't need a tune. I won't be doing a tune on my RS as I find it unnessary. Catted will make less power, but save you headaches if you have to have your car inspected or don't like your car to smell.

So GMG bypass for cost and simplicity.
Or Dundon if you want the best.

Anyway, that's my 100 or so hours of trial and error testing process in my pursuit in finding the best exhaust. My newly acquired RS is awaiting new Dundon center section in order to install the full exhaust at once.

Originally Posted by BrntRubber

Has anyone verified the claimed performance gains from the IPE website?

Originally Posted by CAlexio

Great explanation mAtt, so is there value to buying the catted Dundon version?.. it seems that you are ok with race headers/no cats bc of where you live, but if we are in an emissions state, just go bypass?

Originally Posted by CAlexio

Great explanation mAtt, so is there value to buying the catted Dundon version?.. it seems that you are ok with race headers/no cats bc of where you live, but if we are in an emissions state, just go bypass?

Originally Posted by 0to60

In today’s world, why would anyone go catless unless it’s track use only. DD without cats is not only unnecessary but irresponsible.

Originally Posted by WheelsB

Originally Posted by Money2536

Based on that logic, I would pose driving a GT3 at all would be irresponsible. Removing the cats and improving efficiency, in trade-off, would offset the increased emissions. At least that's how I sleep at night.

Originally Posted by 0to60

In today’s world, why would anyone go catless unless it’s track use only. DD without cats is not only unnecessary but irresponsible.