Due to emission regulations, Subaru has put restrictive catalytic
converters in the exhaust system. These restrictive catalytic
converters do not allow for optimal exhaust flow to the turbo, thus top
performance of the exhaust system cannot be achieved. Also, removal of
the catalytic converter helps prevent the possibility of damaging the
turbo if the catalytic converter breaks apart. GrimmSpeed’s Up-Pipe
eliminates the restrictive catalytic converter and provides a larger
diameter pipe that helps spool the turbo in a quick and efficient
manner. There is a 10+ whp gain when using the Up-Pipe.
Adding a non-cat'd up pipe is one of the first things you should do to
your Subaru. Arguably one of the best $/HP ratios. Another great
feature of the GrimmSpeed up pipe is that the inlet is gasket matched
so you have a perfectly smoothed out exhaust flow compared to the big
step that that tiny stock inlet has.
The GrimmSpeed Up-Pipe is specifically created without an EGT bung. An
EGT sensor is not necessary. If you would like to keep tabs on EGT
temperatures the correct place to do it is on the exhaust manifold
right after the exhaust ports, this is the only place where the correct
temperatures can be taken.
The entire Up-Pipe is made of 304 SS and has a pipe-wall thickness of
2.0mm. The inlet size is 1.93" and the outlet size is 1.72". The pipe
tapers down to 1.72” and acts as a funnel as it moves into the turbo
allowing for the smoothest transition and best air-flow quality. The
flex joint is not located in the bend, which adds to the life
expectancy of the flex section. Our outlset size is a perfect match to
the most common stock location turbos allowing for a smooth transition
into the turbo.
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