Snicker

So I have a 2018 genesis g80 sport, with the 3.3L twin turbo v6 with awd. Factory it comes with true dual set up but it's weird first off has 4 cat's, primarily and secondary. Off the turbos is 2.5 inch pipe that comes down till about the middle then reduces to 2.25, then goes the the back axel where there are 2 resonators one on each side then connect together using h-pipe. Which it weird when normally h-pipe should be at the front near the trans. But anyway then it reduces to 2 inch to the rear 2 mufflers at the back before the bumper. Super quiet and super restricted. This is factory. Has plenty of but dyno pedal feel. After a few months of ownership I had a custom exhaust set up installed. One for more power and less restricted flow but to where there was little drone. And not void warranty and still pass emissions. First I keeped the factory cat's In place primary and secondary cat's. Primary are monitored secondary are not. Both 2.5inch pipe just after the secondary cat's is welded a 2.5inch x-pipe right at the end of the trans output shaft. Then travels back 2.5 inch to the rear axel where there are 2 2.5inch resonators, perforated core not louvered. Then from there the exhaust runs under the axel 2.5 inch then back up using factory hanger locations. Up to the factory rear muffler locations where I have 2 borla s type round mufflers. Mufflers are straight through design and perforated not louvered. And the out the bumper. So effective making a true dual set up with xpipe 2 resonators and 2 mufflers. There is a little drone but it's not ridiculous. But as far as power the but dyno don't lie there is power for days. Launch is instant since turbos are small and still has both factory cat's and it still wants to pull hard. Pulls harder than with factory set up exhaust. Sounds better. And no cel lights no havi g to worry about failing emissions either. So yes as proof u can run an x-pipe or hpipe with a twin turbo set up. The issue is with location and placement. Factory places the h-pipe at the back axel when it should be twords the front near the Trans. Second piping size. U want ur exhaust pipe size to match the diameter of the output size of ur turbos. So if the output size of ur turbos is 2.5 inch then u want ur exhaust system size 2.5 inch all the way back. If 3 inch turbo output then 3 inch all the way back. Unless of course routing and clearance is an issue. If u can only run 1 pipe and u have 2 2.5 in turbos then I'd run a y pipe that had 2.25 inlet on each side to a 3 inch single outlet then run that all the way back till u have room to open back up with a nother y 3 inch inlet to 2.5 dual out. U shouldn't have a problem. I left my cats on not just for emissions but also to prevent overboost or boost creep, When u straight pipe. I Also to still have the low end grunt with no turbo lag. Xpipe also gives a more exotic sound to the exhaust h-pipe has a more classic muscle sound.

Old Buzzard

" I left my cats on not just for emissions but also to prevent overboost or boost creep. When u straight pipe. Also to still have the low end grunt with no turbo lag".
Huh?

Snicker

Boost creep is defined as a condition of rising boost levels past what the predetermined level has been set at. For example, if your target boost level is 15psi, you would see the boost levels increase beyond that as RPMs increase. The short explanation for boost creep is that the wastegate is not able to flow enough air to bypass the turbocharger’s turbine housing. When the volume of air flowing through the turbine housing continues to increase, boost will also continue to increase. This is undesirable and even dangerous for several reasons.This boost creep or overboosting can exceed the factory fuel system’s capacity. This can result in dangerously-lean air-fuel ratios which can lead to engine damage. Excessive boost can also cause detonation that cannot be effectively controlled with the factory ECU’s normal response methods (reduced timing). If extreme detonation has been observed, from poor fuel quality or excessive boost, for example, one of the factory ECU’s methods for protecting the engine is to lower boost to the mechanical minimum. When the system exhibits excessive boost creep, this is no longer possible and engine damage is likely.For all of these reasons, use a downpipe with a high-flow or OEM catalytic converter. This will not only help meet emissions test standards, but also for performance and safety of the car. ( using a catless downpipe can cause boost creep, or uncontrollable boost). This is typically something that tuning cannot fix as it is a mechanical issue that can only be resolved with a catted downpipe.

Old Buzzard

Absolutely

Ls1Rx-7

iTrader: (4)

Agreed, that’s absolute garbage info. If you cant control the boost with a catless downpipe then you need a better controller and bigger wg. Cats slow down the velocity of air which would make it spool slower reducing that “low end grunt” bs you claimed earlier.

back to the original topic, im gonna do a low mount twin setup and im going with an x pipe after the turbos to even out the exhaust pulses and reduce some noise. Im a welder and will be putting it on a dyno to be tuned when im done, i can make some turndowns with the same muffler to test out if there are any power differences between the two setups for some real world data. Will post back in here when I get it all together.

Snicker

first of all it's not bs, as I am using stock turbos wastegates are manufactured into the turbine housing, which don't have an external wastegate. So when using stock turbos u have to rely on certain things as proper exhaust set up and since u don't believe it. There are a lot of performance tuners that will tell u the same I'm on stock controller, stock turbos. And without a little back pressure u can run into issues. U can even Google it. If ur running bigger than stock with and external wastegate then u can control the boost better but on stock turbos with built-in wastegate at the hotside housing. Then u will have issues.