The 5 most common mistakes made when upgrading your exhaust
1) Buying a bolt-on, jig made exhaust - We constantly have people coming in to the shop who have tried to save money by buying a bolt on ready made exhaust for their car only to find they don’t fit well and usually sound terrible. They will ask us to fix the problems but most times we can’t cut and weld them because the metal is so thin the welder blows holes in it. Even if we could fix them, the extra cost means they have spent more than they would have if they had bought a custom built system from us, in the first place. These bolt-on systems are usually made in China and look pretty and shiny on the shelf, but are very poor quality, and are sometimes no cheaper than our custom made systems. With a custom system, we build it on YOUR car, so it fits perfect and we tailor the sound to suit YOU by using a combination of quality mufflers and designs that achieve the sound and look YOU want.
2) Going ‘too loud’ with a performance exhaust – A common mistake is choosing a system based on the sound level from outside the car. DRONE is something that seems to get worse the longer you put up with it. This is another problem with bolt on systems as, for example, a Commodore sedan with a manual transmission will have a different exhaust to an auto, or a wagon/ute etc. For example, using a system that is too loud, on an automatic wagon will create a harmonic drone inside the car, that will frustrate even the most tolerant person.
3) Choosing mild steel over stainless steel because it’s cheaper – If you plan to keep your car for longer than 3 years, and you don’t drive it every day for long distances, a stainless steel system will be more economical because you won’t replace it again. As condensation builds up in the exhaust, a mild steel system will corrode unless it is used often, for prolonged periods of time. Stainless steel however, will not rust/corrode due to this condensation.
4) Wanting a mandrel bent exhaust on a street car – The average street car spends most of it’s time between 1000rpm and 3000rpm, with the odd squirt from a set of traffic lights spinning to maybe 5000 or 6000rpm. With a well designed press bent system, horsepower losses are practically unmeasurable, and certainly doesn’t warrant the extra expense of a mandrel system. If you were constantly at 4000 to 6500rpm a mandrel system would certainly be recommended.
5) OVER EXHAUSTING – This is the most annoying trend at the moment. When combustion happens in your engine, your exhaust gasses are extremely hot and expanded, as they travel down the exhaust they cool and therefore shrink. Having a 3” diameter pipe from the front to the back of your car doesn’t make sense. The gasses actually slow down, causing drone. Over exhausting will cause a loss of torque under 3000 RPM (where most of the work is done). At 4000 to 6000rpm on the dyno it will be fine, but in real world conditions when you need bottom end torque, it will cost you as well as a loss of economy!
This is more noticeable on, for example a V8 commodore, with the standard 2 1/4” front pipes and cat convertors still in place, where a 3” dual cat back system has been fitted. Think of reticulation or fluid flow, you always go from a big pipe to small pipe to gain pressure and fluid speed, the fundamentals are exactly the same when it comes to exhaust flow.
In summary, every car is different and every owner is different, so let us design a system to suit YOUR combination. One size doesn’t fit all !