Matt H Posted January 16, 2007 Share Posted January 16, 2007 When i bought my supra it had the second CAT removed, not long after i had the first CAT removed so it was straight through. Ive been living with it since i had it done but i round of questions from a couple of people saying whats that noise has kinda made me think i might as well ask. Since the first pipe was decat'd there is a very noticable hum between 3k and 4k RPM, which is due to the first decat pipe. Is this normal? or is the installation possibly not 100% causing this strong humming sound? Ta Quote Link to comment Share on other sites More sharing options...
Guest mk47 Posted January 16, 2007 Share Posted January 16, 2007 your car exhaust note definately changes after removing cats, with just the 2nd removed its a bit louder, and with them both removed its even more louder. nothing to worry about. check underneath if you get a chance to make sure its not blowing, but apart from that its pretty normal to make a different sound. hope that makes sense Quote Link to comment Share on other sites More sharing options...
Matt H Posted January 16, 2007 Author Share Posted January 16, 2007 Its not an exhaust type of noise though, its a high pitched tone. Yeah your exhaust note gets raspier and louder after double de-cat but this is not what im refering too. Quote Link to comment Share on other sites More sharing options...
Homer Posted January 16, 2007 Share Posted January 16, 2007 When you say 'hum', do you mean a vibration sound or a drone? What does you full exhuast system comprise of (decat pipes, inc diameter and cat-back) Quote Link to comment Share on other sites More sharing options...
Max Headroom Posted January 16, 2007 Share Posted January 16, 2007 I think I know what you mean I have an RSR with 2nd decat and at around 3000rpm the note of the exhaust under the middle of the car, or so it seems changes note to a "hum" and then disappears. I think it has something to do with the resonance of the exhaust pipe and as such I can live with it. Quote Link to comment Share on other sites More sharing options...
Irvy Posted January 16, 2007 Share Posted January 16, 2007 similar to mine - i have a full decat with blitz exhaust...never noted the rpm but around 80 - 90 it hums - hellish if you have the beginnings of a headache or the aftermath of a hangover!! Quote Link to comment Share on other sites More sharing options...
Homer Posted January 16, 2007 Share Posted January 16, 2007 IMO, the RSR has very little if no drone (never had it on mine, while BPU or single), but the NUR Spec R is VERY prone to it for some reason. Quote Link to comment Share on other sites More sharing options...
Max Headroom Posted January 16, 2007 Share Posted January 16, 2007 Sound waves are a strange thing !! Quote Link to comment Share on other sites More sharing options...
Matt H Posted January 18, 2007 Author Share Posted January 18, 2007 so we would say its normal then and nothing wrong with the way its been installed? Quote Link to comment Share on other sites More sharing options...
Ian Ian Posted January 18, 2007 Share Posted January 18, 2007 Nope nowt wrong with it Matt, its just the sound waves resonating around the inside of the car I bet Dr Dooms is far far worse LOL Cheers Ian Quote Link to comment Share on other sites More sharing options...
Mike M Posted January 18, 2007 Share Posted January 18, 2007 3 - 4k , is that not when the EGCV opens up. That certainly changes the exhaust sound. Same as when running in TTC it's raspy and abit buzzy sounding. Quote Link to comment Share on other sites More sharing options...
Getrag Posted January 19, 2007 Share Posted January 19, 2007 I have a custom straight through and also notice that particular hum at 3k. I quite like it actually. If I'm making progress and happen to change up a gear, dropping the revs to about 3krmp, its particularly noisey. Quote Link to comment Share on other sites More sharing options...
Dr_Doom Posted January 19, 2007 Share Posted January 19, 2007 Nope nowt wrong with it Matt, its just the sound waves resonating around the inside of the car I bet Dr Dooms is far far worse LOL Cheers Ian I couldn't tell how loud mine was due to the blood trickling out of my ears! lol ... I've put the second cat back in though now so it's not quite as loud! Quote Link to comment Share on other sites More sharing options...
Dr_Doom Posted January 19, 2007 Share Posted January 19, 2007 I'm planning on putting the 2nd decat pipe back on again soon, just for the day though. Gonna make a video going through the tunnel at Manchester airport.. I think it'll give that video clip of the Carrera GT a run for its money Quote Link to comment Share on other sites More sharing options...
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