Questions after converting from SSIs back to stock exhaust
 

About 10 years ago I installed SSIs and a single outlet muffler on my 86 Carrera. At that time I did some dyno testing to quantify the performance improvement and had the SW chip customized to insure proper AF ratio at full throttle. I was generally happy with the performance and the sound, except it always seemed to be lacking torque at low RPMs when launching the car.

The car spent the last 10 years in various states on the East coast, as a track/autocross car, where no one cared about emissions testing.

I recently moved back to California and re-installed the stock exhaust to pass the smog check.

After driving with the stock system, my impression is that the stock system does indeed deliver more torque at low RPMs and light throttle.

I assume the higher back pressure of the stock system is the reason for the difference. Perhaps it is something else?

I'm considering re-installing the SSIs (smog checks are every 2 years here) but I'm wondering if anything can be done, such as a different muffler, to improve the low end torque?

Any ideas are welcome

I'm curious, did you chart torque on the dyno?

I'm considering buying some SSI's to put on my car but I ultimately don't want to sacrifice low end torque. I suppose if you're running a factory sport muffler or one like a M&K you could always go to a stock type 2 in 1 out which would quiet the car down and I would assume it would also be a little more restrictive.

I have considered putting my stock 1 in 1 out back on my car and taking it for a dyno run just to see what I have for a baseline with the only exhaust mod being a cat delete. After that I'd install the SSI setup with my 2 in 1 out and do another pull. After that I'd have a custom chip installed and do one last pull to see what gains my money just bought me.

I'd be interested in your SSI's if you decide not to put them back on your car.

interesting -- my understanding was that since the porsche exhaust that the SSIs were based off of was designed for early, small displacement, engines the SSIs are undersized for the Carrera's 3.2 and that running SSIs gives up a bit of high end power but that this restriction gives a bit more midrange/low-end torque than a stock system. (but what do I know, I'm still running a stock exhaust on my carrera . . .)

I've driven quite a few Carreras and not all are created equal as far as low end power. Of the ones that felt snappy, they all had the stock exhaust.

I would concentrate on the intake. Your air flow meter may be the problem or your mixture may be off.

I have ssi on my 3.4 which is a definite no-no if you believe everything you read.

With dc20 cams (maybe this is the difference) low down torque is definitely an improvement over the stock setup. Maybe ive lost something at the top end, but for my road car, they work very well.

Guy to ask would be Steve Wong. "I" have always "heard" that SSIs were a waste of time and money on a 3.2 but that is just what I have heard. Dyno numbers would be best.

You issue isn't with the SSI it's with the muffler. Unless you're doing intake modifications and a hotter cam etc, a free flow exhaust will make it feel limp down low. A Dansk Sport or even an early OE two in 1 out is a perfect companion to the SSIs with lots of low end for AX events. Yes, at the expense of top end.

SSI's are not a waste a money on a 3.2, they clearly work and work better than stock, they're a work of art and if you need heat, there's no better way to go. Given the option, and if you don't need heat, there are better and cheaper choices. I was fortunate enough to have my car come with them installed by the PO and went through a couple of flavors of mufflers.