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      02-10-2012, 03:49 AM   #7
B005T3D-G
Class Leading Reprobate
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Scotland
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Drives: Impreza STi - E92 335i (56)
Join Date: Oct 2011
Location: Mintlaw, Scotland

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Quote:
Originally Posted by doughboy View Post
OP, agree with others, just fitting DPs really makes the car sound different, you might want to do that first. (DEcat DPs are louder than catted obviously)

Re the CATs, the primaries are the main restriction by miles as they are smaller and right up by the turbo. They are there to heat up quickly and pass the cold start 2 minute emissions type-test (cold start emissions not tested at MOT).

The secondaries are much larger and more high flowing. They will pass an MOT on their own as long as they are warm (as proven on here by Phil200tdi).

Plenty on here running way over 400bhp with secondary CATs on.
Coolio . Seems like I might be able to save a few more £££'s towards my LSD. Cheers
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