After 10 years, my first real major repair to my Saab (2000) will be to have the exhaust system replaced (catalytic converter back).
I thought about buying performance items, with the goal of slowly transforming the car into a speed machine, of sorts. (The Saab is no longer my primary car).
I thought I would start with what needs replacing, but I heard that the money poured into an exhaust/muffler is one of the least cost-efficient ways to increase horsepower.
To illustrate: cat back universal exhaust system (no brand name given) at my local shop is $175; cat back Saab OEM is like $550, and a recommended after market is like $425.
Of course, I have friends who don’t believe in exhaust systems and are recommending a bypass, claiming that I’d get more horsepower and not spend any money.
Anyway, I was thinking about saving the money and buying a chip that I can remap if need be as I slowly buy parts.
Assuming that I want to stay compliant with federal mandated laws regarding car emissions, is it worth it to put the money in now, or should I wait until I actually start a real modification, like the heads or gaskets, etc.?
Assuming you are in the US…
Is your SAAB a turbo? If so, a performance catback will make some difference, especially if it is of larger diameter, depending on your power goals. Anything to reduce backpressure will be helpful, and may even increase your gas mileage in normal driving. If you are getting a cat-back (replacing the exhaust system from the main catalytic converter back to the end of the car), it will not affect any emissions equipment. Any local regulations, like CARB certification, is a different matter, however.
Normally, when modifying a car, you works from the ends in. So, you start with exhaust and intake sides, and gradually move in, replacing parts such as turbos, manifolds, heads and finally on to engine internals. Modifications to the ECU can come at any stage, but becomes more and more important the more you modify. The ECU settings may need to be modified multiple times as you progress though performance stages, and eventually you may even need something with greater control over ECU function that your factory one allows. Again, this all depends on your goals for the car, and only applies to the power aspect of a build. Keep in mind you may need to replace/upgrade wheels/tires, brakes, transmission, suspension, etc. A 500 HP car with suspension designed for a 200 HP car is sometimes undesirable.
The advantages of OEM and top-quality aftermarket pipes and mufflers are that they fit nicely, have the proper flow characteristics, and last a long time. While the universals won’t necessarily have problems in those areas, I’d be rather surprised if they didn’t. As to the universal exhaust affecting emissions, I’d think not; as to it affecting performance, that’s possible.
Catalytic converters are a different realm; many cars are quite sensitive to having a proper spec converter and will set trouble codes and activate the check engine light with a universal cat.
A less restrictive exhaust system will, without a doubt, improve performance and MPG. However, the degree to which both will improve will not be felt/realized in normal driving (unless, of course the current exhaust system is overly restrictive).
To illustrate…I built/installed cold air induction system for a '56 Chevy that I frequently raced. Based upon my Elapsed Times and MPH before and after, I picked up close to 20 HP. However that HP was only realized at full throttle and even then it’s not something I felt in the seat of my pants. It only manifested itself on my timing slips. Driving on the street it was impossible to detect the additional HP.
Back to an exhaust system on a relatively low HP Saab, any increase in HP (probably less than 10)would not be felt. I’d recommend finding an muffler shop frequented and trusted by local “hotrodders” and have them fabricate something for you. You’ll get a good system for less money.
Check the manufacturer specs. Ensure the catback is for your turbo engine. I’ve owned a turbo before that was not programmed to work with a less restrictive exhaust (reduced back pressure). A remapping was required (and not available).
The only catback system I can say that seemed to work was on my truck (Magnaflow). Made a clear difference when towing. Other than that… just provides a nice tone/rumble/whatever.
While I don’t necessarily believe very much in the “high performance” claims of fancy aftermarket exhaust systems, keep in mind that they’ll usually have a more agressive sound and nice-looking tips. That may or may not be of interest to you.
“Cat-back” is usually, at least in my experience, everything after the catalytic converter. That is, the intermediate pipe, muffler, tailpipe (if any) and the associated clamps and hangers.
The prices you mentioned sound like they do not include a new catalytic converter.
If there’s any confusion as to whether or not your catalytic converter needs to be replaced, be sure to find out, as it will change your costs quite a bit.
