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Acree · 04-06-2014, 08:08 PM

JDL UEL Header Install

After a brief couple of days of contemplating selling the JDL UEL header or installing it, I just said screw it. Friday night, I headed over to @h4nh's house to install it. We had an issue with the rear o2 being seized in the stock header. There was a surprising amount of corrosion on the threads for a car with only 26k miles and 2 track days. We finally got it on and checked for exhaust leaks. Thankfully, it sounded like all the gaskets sealed correctly. We reused the stock head to manifold gaskets without issue.

The current combination on the car is stock tune, JDL UEL catless header, stock overpipe, ARK Catless Test Pipe, and ARK Grip Exhaust.

The Good: The JDL header has seemed to open the car up significantly. It has some noticeable increase in the torque dip and top end. The problem is I'm still slightly irritated with the torque dip and lag in throttle response. I'm still on the stock tune. I'll be placing an order for the OFT tomorrow.

This exact exhaust combination has me torn. As far as driving comfort and civility in the cabin, it's a fantastic combo! The helmholtz chambers on the ARK pieces really seem to do their job. If I'm on the highway cruising at 75, you literally cannot hear the exhaust with the radio off. It's completely silent which is quite surprising. If you downshift and bury your foot in the throttle, the exhaust screams. It's the best of both worlds. Downshift throttle blips result in a fantastic bark.

The Bad: The combo seems raspy at all RPM values under high load. Honestly, this was something I was half expecting but optimistically hoping I could avoid. Some people like or tolerate rasp. For me personally, it's not acceptable on any car. I think it makes the car sound like a POS. I'm going to have to figure out a solution. I love the exhaust and I love header. I believe the problem is the lack of an inline resonated portion anywhere in the exhaust. The helmholtz chambers do a great job of isolating harmonics and preventing drone, but they do not serve the same purpose as an inline resonator chamber would serve. I think I'm going to purchase one off of Summit and have an exhaust shop weld it into the ARK Test pipe. Obviously I'll keep the interior diameter the same throughout, but leaving the exhaust as it currently sits is not an option. At the same time, I want to avoid adding a HFC. An inline resonator chamber seems like the best option.

04-06-2014, 08:08 PM	#114
Acree Senior Member Join Date: Jun 2012 Drives: 13 CSB BRZ Ltd Location: United States Posts: 1,035 Thanks: 147 Thanked 530 Times in 286 Posts Mentioned: 39 Post(s) Tagged: 0 Thread(s)	Acree's BRZ - The product of boredom and an EE degree JDL UEL Header Install After a brief couple of days of contemplating selling the JDL UEL header or installing it, I just said screw it. Friday night, I headed over to @h4nh's house to install it. We had an issue with the rear o2 being seized in the stock header. There was a surprising amount of corrosion on the threads for a car with only 26k miles and 2 track days. We finally got it on and checked for exhaust leaks. Thankfully, it sounded like all the gaskets sealed correctly. We reused the stock head to manifold gaskets without issue. The current combination on the car is stock tune, JDL UEL catless header, stock overpipe, ARK Catless Test Pipe, and ARK Grip Exhaust. The Good: The JDL header has seemed to open the car up significantly. It has some noticeable increase in the torque dip and top end. The problem is I'm still slightly irritated with the torque dip and lag in throttle response. I'm still on the stock tune. I'll be placing an order for the OFT tomorrow. This exact exhaust combination has me torn. As far as driving comfort and civility in the cabin, it's a fantastic combo! The helmholtz chambers on the ARK pieces really seem to do their job. If I'm on the highway cruising at 75, you literally cannot hear the exhaust with the radio off. It's completely silent which is quite surprising. If you downshift and bury your foot in the throttle, the exhaust screams. It's the best of both worlds. Downshift throttle blips result in a fantastic bark. The Bad: The combo seems raspy at all RPM values under high load. Honestly, this was something I was half expecting but optimistically hoping I could avoid. Some people like or tolerate rasp. For me personally, it's not acceptable on any car. I think it makes the car sound like a POS. I'm going to have to figure out a solution. I love the exhaust and I love header. I believe the problem is the lack of an inline resonated portion anywhere in the exhaust. The helmholtz chambers do a great job of isolating harmonics and preventing drone, but they do not serve the same purpose as an inline resonator chamber would serve. I think I'm going to purchase one off of Summit and have an exhaust shop weld it into the ARK Test pipe. Obviously I'll keep the interior diameter the same throughout, but leaving the exhaust as it currently sits is not an option. At the same time, I want to avoid adding a HFC. An inline resonator chamber seems like the best option. __________________ 2011 BMW M3 (No torque dip) 2013 Subaru BRZ - SOLD - Build Thread Last edited by Acree; 04-07-2014 at 12:32 PM.