fabric

One of the guys near me has straight pipes - no mufflers or cats, not sure about the x-over, and when following him, the car didn't sound overly loud, even when he opened it up. Not sure how it would sound from outside the car,but nowhere near as load as a harley sounds when I hear them while in my car.

Ketchmi

Hey Dave, the idea was to get rid of cats...our system allows the same "adjustability" of going cats or catless.

DR

>Hey Dave, the idea was to get rid of cats...our system allows the same "adjustability" of going cats or catless.

My bad, I thought the customer had to cut your pipes in order to add cats. I didn't know you had changed to my Original Modular design that doesn't require cutting or welding by the customer to go one way or the other.

928drvr86.5

Come on Whitefox.... you know you want my used but nice 928SP H-pipe

DR

Ben,

>Come on Whitefox.... you know you want my used but nice 928SP H-pipe

That is the best and most cost effective solution posted for Whitefox yet!!

Ketchmi

Your origional modular design? Cmon' Dave, I'm sure it was your idea for your crossover but it's certainly not a new, fresh idea. It was in my design specs from day one. We sell them without cats in one piece to save the hassles, extra clamps and flexible joints, they can be modified for cats at that point. If we sell them with cats they come cut off and have a slip on design "similar to yours" that's been in use since exhaust systems were invented. There is no welding required on mine and they can be modified after purchase to include cats by cutting the rear 11" off if you change your mind and want to be emissions legal.

Say, didn't you invent the internet too?

Jim_H

If you remove your cats the North Pole will melt...

EB338

If you keep the cats too long your whole car could melt

DR

Dave L,

Merry Christmas!

Gretch

Eeeeeasy boys.....

928Collector

I want my 1979 Shark to sound like this: vvvrrooommm!! VVVRROOOMMM!!!! POP!!!! POP!!!!, CRACKLE - CRACKLE!!!!!!

Stylistically, I want my exhaust acoustics to be a very very loud, deep growl, rich.

Do i start with a muffler delete for a louder note?

Then a cat delete? But will a cat delete cause the dashboard warning light to go on? does removing the cats improve a deeper / richer sound?

What about installing a megaphone exhaust tips?

And someone said leave the resonator on to create back pressure?

I'm not interested in replacing the headers at this time.

Any advice thoughts on specifically doing this for a K Jetronic 928 much appreciated.

hacker-pschorr

That's a good place to start

It's all personal preference. Often times no cat = drone, but that can usually be fixed with a resonance pipe added. You really need to try both or a combination of to see what you like.

As for warning lights, no, that won't happen. These cars do not have a CEL to speak of nor a secondary O2 sensor to sense the removal of a CAT.

Only you can say if that will sound good or not.

Backpressure being needed to make power and / or torque is the oldest wives tale still around for the performance industry. This has been debunked 1,000+ times over.

WestInc

928Collector:
Since you have an older car i suggest looking into this thread:
https://rennlist.com/forums/928-foru...any-views.html
There we discuss some exhaustoptions to ob cars. My car is a 1983 928s euro k-jet. The system sounds very much like you describe you want, maybe not as loud as you want. In that thread I also have a soundfile uploaded, put some nice headphones on and listen. I think you will like it...

Shirah

I was told a properly tuned car will not cause pop/crackle or gunfire sounds.

Additionally, be careful where you make your car sound like gunfire. Someone may return fire (as in my state),
scare pets or folks with PTSD.

Sorry, couldn't help myself

hacker-pschorr

There are technically 3 different variations of "OB" and I can speak from personal experience, each one can have it's own unique exhaust sound. If you want to compare apples to apples, need to know if your car is L-Jet, CIS, or LH.

Very true, but we're talking about cars that cannot be "properly tuned" without going to a standalone ECU (exception is the 85 EuroS).

The CIS cars have no fuel cutoff, so when you slam the throttle shut on decel, raw fuel is sprayed into the exhaust.

L-Jet cars have an idle switch, when activated momentarily cuts fuel. If you disconnect this switch.....you can make all kinds of fun noises without a CAT installed.

Some cars also have a decel valve (LH cars do not and I don't recall what's on the CIS TB's) on the throttle body which slows down the RPM drop when the plenum sees vacuum above a certain level. If this has failed, or has been removed, will affect how the exhaust sounds on decel.

The 84-85 EuroS has LH and EZF which manages all the above electronically. The 84 brains cannot be SharkTuned, the 85's can.

Here is what a 79 CIS car with headers, open 3" exhaust and no decal valve sounds like on the track (my car)