FL5 Civic Type R Exhaust Design Blog #1 - To Valve or Not to Valve

The brand new FL5 Civic Type R has been on dealer showroom floors for about 9 months or so now. How many do you think are still sitting on those same lots Because of outrageous markups that the greedy dealerships can’t seem to let go of? Nevertheless, product development must proceed! For today we are going to take a closer look at the underside of Honda’s flagship car.

For 2023, the Type R is a completely new car (clearly). While the engine and the transmission remained mostly the same as the year before there was no shortage of enhancements throughout the chassis from bumper to bumper and the exhaust was one of them.

The team here at 27WON has already confirmed that our high flow race catted downpipe from the FK8 is a direct bolt-on for the new FL5. This is a great first modification as it frees up a lot of HP and TQ.

It replaces the restrictive OEM unit with a much larger unit for less exhaust back pressure. Let’s take a look at the rest of the exhaust system and see how it stacks up starting with the front-pipe.

The OEM front pipe is actually a really nice unit. It’s a healthy size, has a nice flex section to account for engine movement, and is secured with 3-bolt flanges on either end. As with all things OEM Honda, it fits in there perfectly and provides a simple and easy way for exhaust gasses to get out from the downpipe to the rest of the exhaust system. The front pipe itself mimics that from the FK8 and does not have any unnecessary bends or kinks in it that reduce flow much. When we consider an upgrade here we take into account the long term play. If you will you go with a bigger FMIC or Kuro turbo Upgrade then you’ll want to open up the exhaust system to let it breathe. We REDEFINED the FK8 with our full 3” exhaust to eliminate exhaust back-pressure and increase power output so you can count on our team to do that again. We will optimize size to be big enough to not impede flow but not so big to add unnecessary weight.

Moving on down the line to the midsection of the exhaust system and you see the same setup as for the FK8. The pipe measures the same as the FK8 at just under 2.5” inches or 60.5mm (2.38”). There are two resonators; a small one up front and a longer one towards the rear. This is a solid setup that is well tuned and delivers a good sound for a factory equipped exhaust. We know the FK8 and new FL5 can go north of 600whp so bigger piping is appropriate here. How big has yet to be seen.

The axle back is where we see the biggest difference between FK8 and FL5. The FL5 axle back is much more compact and straight through. For the FK8 the middle tip did not do anything. It was not connected to the exhaust piping so exhaust gasses do not actually flow through it. On the new FL5 it is connected to the main exhaust pipe.

Now for the FL5, not only does that middle tip flow but it is valved! Yes you read that right. The FL5 exhaust is valved from the factory. This feature used to be only found on high end sports cars. This valve is electronic and is commanded open or closed via a drive setting.

You want comfort and quiet – it stays closed. You want all out Type R track performance and it opens up.

I have always had my concerns with exhaust valves. Primarily when they don’t work. The idea behind them is great; Quiet when you want and loud when you don’t. I have seen many earlier versions of them break. They get stuck open or closed. Has reliability been improved for these new cars? Probably. It’s Honda after all. But maybe it’s too early to tell. 

Are you looking for an upgraded valved aftermarket exhaust? We want to know your thoughts so please leave them in the comments below. 

The OEM FL5 exhaust is good, really good. Improving on it won’t be easy but nothing in life worth having is easy so we say bring on the challenge. Be sure and stay tuned as we figure out how to get the sweetest of sounds from your FL5. 


-Vincent
Co-Founder