You guys are getting on the right track with the exhaust systems. The
statement that small tubes are for bottom end and large tubes are for top end
is correct. One other thing you have to keep in mind here.......... an
internal combustion engine is effectively an air pump. Its
efficiency/horsepower is dependant on the volume of air it is capable of
moving. Here is my point, overly simplified. you have three basic
componenants to the engine, for the main purpose of processing air. The
aspiration system, the cylinder head and the exhaust system. Increasing the
flow in any ONE area may or may not yield a gain in perfomance. Here is why.
Put numbers to each componenant. Air volume flowing is measured in cubic feet
per minute. In a perfect world, all componenants would flow exactly the same
volume of CFM. In the real world, such is not the case. There is always a
bottleneck, so to speak. Example, say your intake flows 150 CFM, your head
flows 100 CFM and your exhaust flows 200 cfm. Increasing the exhaust or
intake flow would yield no increase in performance because of the bottleneck
at the rate of flow the head has. In performance engine building, they just
constantly chase the weakest link. Improve head flow above exhaust
capabilities, build a better exhaust. Got the good exhaust now? Intake wont
keep up, improve the intake. Intake flows more than the head? More headwork.
On and on. My point to all this is that not only are the exhaust tubes
smaller on the GTS than the FZR, so are the injectors, compared to the size
of the carburetors on the same year FZR 1000. The reason they chose smaller
sizes was indeed to boost low end and midrange ( read that usable) horsepower
for sport touring riding.Smaller tubes increase velocity at lower speeds but
obviously dont handle the volume. To get the same velocity in bigger tubes or
carbs/injectors, obviously, you have to be turning more RPMS to obtain
similar efficiency. My other opinion on a company that produces a perfomance
product dyno'ing it themselves is buyer beware. Dyno's themselves, esp the
less expensive brands, say under $15,000, are quite easily manipulated to get
favorable readings where you want them. We are cuaght in a bit of a
vulnerable position because we are not going to be seeing any magazines doing
independant testing of a NEW HEADER for the 1993/94 GTS 1000 Yamaha. Further,
you can not see what your buddies are using and what works for them, or what
seems to be the hot pipe at the race track. Within reason, bigger pipes will
flow more, and if they are all about the same length, it should work and be
an improvement to some extent for top end horsepower. Whether it is worth the
money/effort to obtain and install becomes very subjective.
I think all that rattling was my $.03.
RSRBOB
