Borla UEL Header : Need some opinion/advice.
 

Hi guys! I've recently installed the Borla UEL Header on my FR-S. This pretty much sums up my exhaust mods for the car - but I have a small issue at the moment. Honestly, I'm loving the sound when the car is in free and not under any load, BUT when under load and especially at lower RPMs the car makes a very (or overly) raspy, high-pitched, almost metallic 'rattle' sound. I thought it sounded great (and very ricey) at first but after a while it started to sound slightly odd. I don't think it's the exhaust components leaking as the sound seems to be non-existent while in free gear (a lovely rumble at pretty much all RPMs), neither were there any whistling. It only happens when the car is under load and can get a bit annoying when I'm trying to slow-cruise like a civilized man. Just a bit more pedal and the metallic rasp comes up; and it gets louder the harder I hit the pedal. I've tried to locate if there are any mechanical rattles or loose flanges but it doesn't seem to be the case. The sound seems to come from the axleback itself (or the axleback vibrating wrongly, I don't know), rather than any mechanical faults throughout the entire exhaust system. Of course, I can be wrong in assuming that and that this could or could not be the actual sound resulting of the combination of my exhaust system. I'm not sure if there's actually a resonator in my axleback - there's too little data on it unfortunately.

I would really appreciate any kind of input regarding this matter! Many thanks in advance! :cheers:

My exhaust set-up:
- TRD (JDM) Quad Tip Axleback
- Stock Midpipe
- Perrin Catted Front Pipe 2.5"
- Perrin Overpipe 2.5"
- Borla UEL Header (Non-catted)
- ECUTek Tune (Last Tune: Before Installing The Header)
- TRD Rear Diffuser (Steel)

I have a very similar situation as yours. Sounds like axle back vibrating. But it's just stock overpipe and catback. But after about a month, the noise pretty much went away. Don't understand.

Thanks for your feedback. After driving for a few more days, I realized that the rasp has toned down slightly (perhaps its carbon build-up in the new header and overpipe?). I'm going to get a retune soon enough and see how that goes. If the rasp persists, I might just swap my frontpipe out for one with both a high-flow cat and a resonator. Thanks :)

Make sure you're always doing an Italian tune-up about once a week. Helps to get the carbon out.