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Old 03-03-2009, 10:26 PM   #1
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Raspy Exhaust (no cats), need advice

A couple months ago, I had the cats taken off and bypass pipes installed, mine is a 98, so it only had one pair.

Inside the car, I think it sounds pretty decent (no drone, barely any louder). I can't say I'm as impressed with how it sounds outside though.

The one thing I was afraid of before doing so was to sound like a ricer, and I think I achieved just that. It sounds like a rattling tin can at mid-high rpm's now.

If I drive very conservatively, the car is pretty quiet outside, the nasty sound only occurs at higher rpm's

I've been doing a lot of reading on here about people who have done the PSE or drilling mods to the muffler (mine is stock, by the way). Anyone have any experience with either of these mods, or something else in conjunction with cat-bypass pipes?

I am not looking for an obnoxiously loud tone, just something a little deeper without the "tin-can" sound.

....I'm sure someone on here will be a smartass and say "Put cats back on dummy!" While I agree, it would fix my raspy, rattling exhaust tone...it's not exactly the response I'm looking for.

Thanks in advance!

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Old 03-04-2009, 07:11 AM   #2
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Have you considered high flow cats? My guess is you've actually decreased power because of the lower back pressure. The engine wasn't designed to run without cats. How do you get around the dreaded CEL or do you chose to ignore it?
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Old 03-04-2009, 08:09 AM   #3
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I don't think the raspiness will go away by changing your muffler. I have heard a 2000 Boxster S with bypass pipes, and a PSE, and it still had some raspiness even though the 2000 model yr. had a set of pre-cats on the headers. I know you don't want to hear this, but to get rid of the raspy sound, you'll probably have to put the cats back on or get sport cats, and then a throatier exhaust to attain the sound you want.

Or, you can get sport headers, put the cats back on, and you'll also yield a throatier sound without the rasp.
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Old 03-04-2009, 09:53 AM   #4
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High flow cats may be something to consider. I got around the CEL by using spark plug de-foulers to pull the second set of O2's out of the stream a little, this works great.

It doesn't seem like I lost any power, if not a little more gain at higher rpm's, but slightly less bottom end torque (barely noticeable).
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Old 05-04-2010, 01:26 PM   #5
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I'm going through the same thing with my 99. I put high flow cats on and it sounds exactly as you described till it gets to full temp, then it isn't as bad. I've pretty much determined that I need to go back to stock but I need a replacement OEM cat first as one had the o2 threads destroied.
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Old 05-04-2010, 04:37 PM   #6
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How many miles on the hi flo cats? I might be willing to trade you. I have factory cats, but would love hi flo ones for my setup.

Steve
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Old 05-04-2010, 04:49 PM   #7
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Has anyone done the Crios mod and bypass pipes? I would think that this might give a deeper sound on an S at least (main cats are in the headers.

I was going to do this but really do not want the er....em dare I say ricer tone..

I am after a deeper flat six grunt...
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Old 05-04-2010, 05:06 PM   #8
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I would say if anything its your muffler. or maybe your taste (no offense meant by that of course)

here is a 2.5 no cats with a different muffler. and IMHO it sounds very good.

precision chassis works exhaust cat delete and muffler.
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Old 05-04-2010, 05:45 PM   #9
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Originally Posted by jaykay
Has anyone done the Crios mod and bypass pipes? I would think that this might give a deeper sound on an S at least (main cats are in the headers.

I was going to do this but really do not want the er....em dare I say ricer tone..

I am after a deeper flat six grunt...
Only the 2.5 cars have one set of cats, any 2.7 or 3.2 has 2 pre-cats in the header, and two secondary cats in the mid pipe.
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Old 05-04-2010, 06:46 PM   #10
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that spec boxster exhaust sounds great.

I also think the vid online of the NHP system sounds pretty good too.

I have a pedro style bypass exhaus ton mine, and it sounds nicer than stock, but it is .. to me... a tad raspy and not quite deep enough. I think to get the sound you're looking for - it's more the MUFFLER and not the cats. you need a diffeent muffler.

i'd suggest looking at a set of headers with hiflow cats - and then add a set of bypass pipes and new ehxaust. the downside is that there's NO cheap way to do this...

Fabspeeds system will set you back a LOT. Even the NHP system, which is far cheaper, is still probably about $2000 for that setup....

when you figure that the average 2.5L boxster is only worth $10k or so - it's a LOT to then spend 20% of the cars value on an exhaust......

it's expensive to be cool.....
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Old 05-04-2010, 07:33 PM   #11
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well since the OP has no cats already since there are only two in the midpipes and he has removed them it is definitely in the muffler. change the muffler... change the sound. I recommend looking at spec boxster setups online because most if not all have testpipes in them (no cats) and some form of muffler. the video sounds great however, you need to buy the midpipes from them to use their muffler.

hi flow cats in my mind are a waste of time and money. so very pricey and you dont lose much weight (if any) and you gain minimal power (if any) at least with a cat bypass you may not gain or lose any power but at least you lose weight. and with this spec boxster system or with an aftermarket muffler that is even MORE weight lost and a better sound.
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Old 05-04-2010, 07:45 PM   #12
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Sounds pretty good to me ........any drone? Yes, of course I wouldn't be able to get this on my 3.2.......I am after suggestions that are streetable for the 3.2.
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Old 05-04-2010, 08:22 PM   #13
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actually, you could get this system because it will fit just the same... except you will have the header cats on your 3.2 so it will probably be quieter by a little bit.


as far as drone... the louder you go the drone will be there they are very often hand in hand. except maybe with some of the highest end of systems.

here is a clip of my exhaust 2.7 still has header cats on but 40 bux for catless midpipe.

but again muffler has ALOT to do with the sound.

Ive raced with a fellow boxster owner in my area (autocross) and he has i think fabspeed bypass with the PSE... to be honest it isnt that much louder than stock... BUT with mine the deluboz muffler already made it louder but the cat delete made it in my opinion great.
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Old 05-04-2010, 09:12 PM   #14
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Originally Posted by Lobo1186
actually, you could get this system because it will fit just the same... except you will have the header cats on your 3.2 so it will probably be quieter by a little bit.


as far as drone... the louder you go the drone will be there they are very often hand in hand. except maybe with some of the highest end of systems.

here is a clip of my exhaust 2.7 still has header cats on but 40 bux for catless midpipe.

but again muffler has ALOT to do with the sound.

Ive raced with a fellow boxster owner in my area (autocross) and he has i think fabspeed bypass with the PSE... to be honest it isnt that much louder than stock... BUT with mine the deluboz muffler already made it louder but the cat delete made it in my opinion great.

This is why you either pony up, or stay stock. The Fabspeed and B&B systems are drone free, and sound fantastic, but are not cheap.
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Old 05-04-2010, 09:31 PM   #15
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its true, those are good systems... however if it came down to it however, id choose drone over BB for 3 grand (which doesnt include midpipes...) or fabspeed from 2500 to well over 4000 ( depends on whether you do sport cats or not)

its robbery simply for the fact that you are not getting a good yield of power to $.
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Old 05-05-2010, 04:24 AM   #16
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Originally Posted by 986rgt
How many miles on the hi flo cats? I might be willing to trade you. I have factory cats, but would love hi flo ones for my setup.

Steve
PM sent. Thanks,
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Old 05-05-2010, 05:33 AM   #17
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If you are hearing rattle noises, I think an earlier poster was correct - your old mufflers are more likely the source of the offensive noise. Old cats and old mufflers can start to come apart internally producing all kinds of rpm dependant noise.
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Old 05-05-2010, 06:19 AM   #18
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This isn't a rattle it is a rasp. It is hard to describe but I've had rattles before and this is an exhaust noise. I've tried two different mufflers in case that was the issue but it wasn't. The noise only was present after I put the cats on and is most noticable with the stock muffler. I could just get the Maxspeed muffler but I really like having no drone.
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Old 05-05-2010, 07:06 AM   #19
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Replacing the stock exhaust manifolds with a set of headers may deepen the sound a bit.
Headers dramatically deppened the tone on my car, however, I have a 2000 S, and had the cats on the stockers.
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Old 05-05-2010, 04:26 PM   #20
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Sorry guys, it's all a waste of money.....drill the holes and spend the money on some other mods.

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