Angel84-928

Didn't know that. I've been planning on dropping the CAT for a "test pipe". Hmmm, need to rethink that now.

ROG100

The Borla is hard to find if not NLA.
The system that Mark Anderson designed to emulate the Borla system is in my opinion even better than the Borla. It even looks like a Borla system and sounds awesome.
I have a Borla system on one of my 82 cars and his system sounds even better.

justin

I just removed my cat and installed one of Roger's Y-pipes. I didnt notice any drop in low end torque, but did notice a big gain in higher rpm's.

PorKen

+1 for 2½"

-1 for back pressure. It's gas speed and density (temperature) that affect flow/extraction. The 'pressure' of pushing cold exhaust through a 3" pipe is worse than any restriction 2½" could make.

Cast iron manifold outlets englarged to the ID of the 32V gasket, slightly larger down pipes (32V 2" versus stock 16V 1¾"), into a single 2½". Stock resonator, and pumpkin with the internal pipes cut out. I found that having a balance pipe before a Y or X acts like a muffler, but doesn't affect power.

The main benefit is from the manifold porting matched to the down pipes. The exhaust has to be smooth all the way through with no big jumps in size.

222 hp/ 287 tq rw-std with the lame 80-82 cams! It's not much louder than stock, and doesn't resonate.

Landseer

Duals.

16V, Dual in/out Cat, a pair of Magnaflow same-side offsets 2 1/4; Rt side and lt side SS pipe 2 1/4; Lastly, Dual-in/Dual-out Magnaflow 2 1/4.

Inside car sounds great, esp. with heavy tar removed, but won't hurt my ears.

Outside car is stealth, unless you are really on the throttle hard.

As Porken would say, mine is a girly exhaust. But I'm ok with it.

Is it best? Depends on criteria.

Angel84-928

What's is the Magnaflow PN you recommend?

Imo000

Add a supercharger to it and you'll think the world is coming to an end!

hopwood

Hi Roger

Where can this MArk Anderson system be bought from?

I'm looking for a new exhaust for my modified 79 (euro S2 engine) and have so far found this

http://www.mailordercentral.com/928i...1%20930%2000SS

Cheers,

Joel

shmark

I've said it before and I'll keep sayin' it. A single has the best sound out there, and it nearly as good power-wise as a dual. I've got the Motorsports Y-pipe into a Borla and it's just awesome, love the sound and no it's not too loud. Highway cruise is not loud at all, but the echo off the walls when you bury the throttle is fantastic. Oh and I can verify that it does compromise low end torque. My car is not as strong below 3k, but it does seem stronger above. It's a tradeoff and I like it.

jleidel

Roger, what mufflers is Mark using for his system?

911tracker85

on my 84 US spec auto I replaced the cats with the Y pipe from Roger not long after getting it. cat pipe rusted and leaking. did not have enough time to tell if removing the cats effected low end torque.

I find PorKen's post interesting. after installing the Y pipe, car definitely louder. what annoys me is how the stock pumpkin muffler now sounds like the exhaust is echoing around an empty garbage can when you back off the thorttle. a lot of burble/pop sounds and a very hollow sound. I was suspecting the internal baffles are rusted out. but when on the throttle it is loud and sounds good. a new cat back exhaust on my wish list, but need to pay Roger for the box of parts I just got to do some more refresh work this winter.

shmark

Had the exact same problem on both my 928s. It's just a characteristic of the factory mufflers - they sound hollow and tinny without the cat. Installing the Borla made all the difference in the world. Really nice fluid sound, mellow at low rpm with a real snarl when you put your foot in it, and no droning/resonance anywhere.. It does pop off-throttle, but that's just a fact of all engines. The factory cat does a lot more muffling than most people realize.

rdisney

When I bought my 80 US Auto, it had a RMB and the rest was stock. loved the sound. I could feel an increase in acceleration around 4KRPM. I replaced the RMB with a stock pumpkin and noticed a little more acceleration off the line. and the 4KRPM bump disappeared.

80 US Auto
80 US 5-speed

atb

I've got the no cat Ansa on my '79 track car . I think most would find it too quiet. It's very smooth and civilized sounding. Its louder than stock but not by much.

GlenL

I'm shocked that no one has offered this advice:

Change to US '85-'86 exhaust manifolds. This will net an actual power increase.

Then go Y-pipe or whatever you need. Those manifolds come back to different places than the stock, cast lima beans you've got on there. Take that into account if you switch manifolds.