| Metric Mechanic
HiFlo Exhaust System
The Metric Mechanic System 300 is an excellent exhaust system that we
developed for 5 & 6 series BMW's from 1979 to 1988 that are equiped
with catalytic converters. This system is also available for the M5
& M6.
This system was originally developed for our larger 3.8 and 4.0 liter
engines. Basically, we knew of no existing system that could properly
unleash the performance of these larger engines. Before developing our
HiFlo exhaust, we were using systems or exhaust parts from European
performance BMW models. Euro exhaust systems for 3.5 liter big six engines
use two 50 mm down-pipes that dump into a dual 50 mm exhaust system.
We liked the way these 50 mm down-pipes helped diverge exhaust flow
away from the 6 cylinder cast iron manifolds. We found that the dual
exhaust system coming off the down pipe worked well on earlier 3.6 to
3.7 liter engines but on 3.5 liter engines it caused a loss in bottom
end torque. We discovered that this low speed power loss could be fixed
if we merged the exhaust system into one large exhaust pipe after the
down pipes (more like exhaust systems before 1976 model BMW's).
Also, by merging into one large pipe, the system dampers out exhaust
pulses better than two separate pipes. This cuts down on the noise level
of the exhaust. With our MM HiFlo Exhaust System, we're able to totally
eliminate the need for a resonator by using this principle. By eliminating
the resonator, the exhaust system is lighter (40 lbs. less than a stock
system) and lasts longer. This is a lot of weight that you no longer
have to deal with when handling or accelerating. Also, with the resonator
out of the system, not only is it one less part that's not going to
fail but the system will run a little hotter and last longer.
Most people probably believe that heat kills the exhaust system but
the real killer is condensation (mufflers rust from the inside out).
Now, how do you remove condensation? With heat! A good example of this
is the 140 or 240 series Volvos. They run 5 mufflers. This cools down
exhaust so much that condensation rots out the exhaust system every
2 years. So, in our system, by eliminating the resonator we've added
life to the rear muffler. |
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