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Exhaust - Phat Boy muffler too loud - advice needed.
Uber Kafer - September 17th, 2010 at 09:40 AM

I have a merged stainless system, into a stainless phat boy muffler. Its a common system available in australia.

Has anyone had any success making phat boys quieter. I expect I will have to cut the muffler off and get another muffler welded on in its place. So I need to know if anyone has had success with a particular size and model muffler. I imagine it wont be too hard to spend as much on this mod as the system cost initially, knowing the prices of stainless exhaust components at our local shops.


Craig Torrens - September 17th, 2010 at 09:50 AM

my advice: sell the system and buy a stainless sindwinder from classic, I found that on my car it was a lot quieter than the fatboy....you should be able to get good $$ for your system so the change over price maybe only be $100 or so. (thats if you like the sidewinder style though!)


Sides - September 17th, 2010 at 09:51 AM

Yeah, Phat Boy's are pretty loud, but what's your definition of too loud.... have you been defected, do you just not like the noise level, or are you trying to get under the noise limit at a track ???

I used to have issues getting under the 95db noise limit when running at tracks, and I solved it by simply putting a 2.5" 90 degree bend on the exit of the muffler... direct the exhaust straight back rather than out to the side. I also had one of those baffle setups from a Monza 4 tip on the end of the bend, but soon ditched that part.

Jezebel is still loud, tho can't be too bad since I live only one block from the local police station and have never been pinged. On the noise meter at the track I went from 96-98db down to around 91db, which suited me just fine.

Cost me a grand total of $15 something for the bend and a bit of time in shed... tho admittedly mine is mild steel rather than stainless.


Uber Kafer - September 17th, 2010 at 10:18 AM

I had considered selling the system but fitting a new one would commit me to an engine pull and I dont have the time to do that right now, and besides, my son has taken over my shed....

so I'm hoping for a mod that just involves some spanners and not too many dollars.

as for my definition of too loud.... lets just say the volume doesnt fit my age and activities. That engine loves to rev and I want to be able use the revs, but not let half the suburb in on the fact. My son reckons he can hear every gear change as I come home from work. Thats sort of cool... but not...

I'm curious about the muffler outlet, it had already occurred to me that if I fitted an exit pipe that pointed more down it might dissipate the bark a bit.


waveman1500 - September 17th, 2010 at 10:36 AM

Pulling the engine only takes half an hour, it's really not that hard. If you really wanted to you could probably get an exhaust on it with the engine still in, but I wouldn't bother. What about trying a Super Trapp on the end?


Uber Kafer - September 17th, 2010 at 11:14 AM

1979 was my first engine pull, so no anxiety there, just a current reality that forces me to keep it simple. I envisage a result that is based on an ugraded muffler and tailpipe. A trapp would be just too exotic around here.


hellbugged - September 17th, 2010 at 11:54 AM

ive used a genie "super turbo" which was great!
Now a magnaflow which is good, not super quiet but way better than the fat boy
Its a simple job for a decent exhaust guy, i just used the pipes from the fat boy, cut and turned it a bit


Uber Kafer - September 17th, 2010 at 12:01 PM

excellent. Thats valuable info. thanks.


1303Steve - September 17th, 2010 at 12:05 PM

Hi

chicken wire really works

Steve


Uber Kafer - September 17th, 2010 at 04:47 PM

"chicken wire !!" I remember a famous scene from 'the Blues Brothers' movie that featured chicken wire.

But how effective is it and how much do you need?


1303Steve - September 17th, 2010 at 10:29 PM

Hi

Just roll yourself up a chicken wire cigar a bit smaller than the muffler pipe and ram it in, the biggest issue is keeping it in there.

On my sons car I scored a 2 inch double inlet & outlet muffler from Westy, its reasonably quiet.

Steve