backitoff

Well guys thanks for the great advice!
I ordered a 100cel cat but can't get it in the timeframe I need, so I have gone for a decat pipe.
I have a new 02 sensor ready and waiting to fit and and I also ordered a 'G' pipe.

Really looking forward to the soundtrack, but worried that it might be too loud.

What do you think?

greg1990964

It this going to be with a cup pipe and g pipe or by itself?

backitoff

Hi Greg1990964
The set up will be:
Cat delete pipe - OEM Primary silencer - G pipe
Thanks

Johnny G Pipe

It will be loud - only you will be able to tell if its too loud! I have the same set up and people will hear you coming (and you won't be able to sneak away from your mistresses house at 5am) - but its not OTT ricer loud.

It is also 'good' loud, rather than noisy. Quite gruff and throbby at low revs, but accelerating through the gears with a high wall beside you, it is just a divine sound. No problems at cruising speed either. Enjoy..

speedbagger

agree--catless should be avoided where feasible, but at least he's not coal rolling...

pcarplayer

have you considered if you will need your fuelling remapped to suit?

Jaye Bass

I have a cat delete and a cup pipe...sounds superb. Another paper cut but then Gaia made us to get plastic.

The reason I got the cup pipe is that it removed the most weight.

greg1990964

I have cup pipe and think doing cat delete also will be perfect. G pipe seems like it would be obnoxious with cat and cup pipe. So my cheap cat delete pipe continues..

backitoff

I only started on this by deciding to fit a 'G' pipe and a new 02 sensor

Good point will need to be done for sure. I need to hear how loud it is, tone etc, then I can decide on what exhaust set up I go with (may swap G pipe for cup pipe) then I can sort the fuelling.
Appreciate the heads up. Thanks!

911Jetta

Cup or g pipe, both sound good but different.

My primary bypass with cat bypass sounds just awesome. It's loud - my town is full of Prius'- but totally acceptable to everyone that hears it. Most people see my 964 as an old sports car, back road racer, so the sound actually seems appropriate and part of the image. No one knows how loud an old 911 should really be, so you can easily get away will a little extra sound. The people working in the parking garage where I park love it too! I also have a drilled airbox and have removed the ugly engine sound pad too. All of that combined adds so much to the experience of the car to me. My kids ride in the back a couple times a week too.... They love it and have NEVER heard the radio in my car in the last 7 yrs.

Btw, I ride my bike to the office over 200 days a year, so I don't feel quite as bad about the cat delete....

kreeshp

Curious if anyone here has run a 100 cell sports catalytic converter + primary bypass + G pipe? I realize that a full bypass exhaust is obnoxious and might even detract from (street only) performance but what about the above combination?

-nick

Ha ha ha. Silly hippies and their bicycles. Meanwhile, outside of the cul de sac, let me tell you how wonderful the air in Beijing is this time of year.

I looked into aftermarket cat options recently. The difference between a good 100 cell cat and a bypass pipe is about 1hp and 1ftlb. Documented on quite a few dyno runs, though non-Porsche. And a 100 cell cat will still give a pretty significant reduction in emissions.

I can only find bolt-on aftermarket cats available through FVD and Fabspeed at the moment. Fabspeed uses German HJS (Emitec cores?) universal cats and welds on the 964 specific flanges. Not sure what FVD does, but odds are that they use HJS too. The Fabspeed price is reasonable given the expensive cores. FVD price is in the stratosphere, as usual, but nobody ever seems to complain about their quality.

The internet dyno says that there are a few other decent universal fit cats. Of note are mil.spec's 100 and 200 metallic cats, eastern catalytic's 200 cell metallic, random technology's 200 cell metallic, and the 100 and 200 cell hjs metallic cats. They are all decently priced, except the hjs.

Of note to avoid are magnaflow's cats. Not sure if they are all bad, or only some of their versions, but lots of chatter about short lifespans and severely underwhelming dyno results.

According to a few fabspeed posts, some 100 cell cats have internal reinforcement that completely negates the freer-flowing cell count. They're a fan of the 200 cell HJS. Though I don't know how HJS compares to some of the "good" vendors listed above. Other than being about 2x the core cost. Something tells me that they're doing something different to justify the cost.

To compare, the stock 964 cat is 400 cell ceramic. Metallics are supposed to be longer-lasting than the ceramics.

Oh yeah, and a bypass is illegal. The fine is not small for failing a visual emissions inspection in the US. It took those nostalgic days of 1970's/1980's SoCal smog, among other US travesties, to institute these regulations. Take a look at your kids and think about asthma. Convinced?

mrmandmman

I just purchased a fabspeed cat. Have a primary bypass already. Might take me two more months to get my engine back in my car but I'll let you know how it sounds when I do.

I'm in agreement with -nick, I'm all for enjoying our cars but why do so at the expense of increased hydrocarbons (smog), carbon monoxide, and nitrogen oxides (smog + acid rain). It will be interesting to see if the emissions changes between a 400 cell to a 200 cell.

pcarplayer

AKAIK, strictly speaking that was a long g-pipe and the attached is pic is a swan neck...

backitoff

Well guys I had the time to fit the Cat delete and G pipe this weekend, and what a great noise!!
It has a real deep burble on tickover and when you rev it it sounds amazing!
I am so pleased with the noise as it seems just about perfect for me. Not to loud and quite refined! Superb!!

Thanks everyone for all the help and advice!!