Quote:
Originally Posted by Kiwi Peter
I replaced a mid pipe last week on a IM so i did a comparison of dumps looking from the dump outlet as we have many stock cats in stock  .
I could not see any difference, the cat component looks the same as a stock 135/335 cat, i reckon the extra power comes from a better tune i guess time will tell.  |
I’ve done the same and also have some cut out mid pipe cats here. The 1M and 135i cats in the DP’s look identical to one another. They also look identical to the mid pipe cats I’ve got here. I’d wager the different part numbers are perhaps different cone angles/dimensions for the front/rear of the cats or something minor like flange angle.
I’ve crudely measured the mid pipe cats with a small piece of cardboard with a ruler drawn on and got 440cpsi.
Quote:
Originally Posted by Zuzu
In which way.. Do we have any hard data to justify this claim.
Does the 1M have less restrictive high flow cats as OEM, as the actual 1M DP's are very similar to the 135i/335i.
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No hard data that I’ve seen. Mine are still visually the same as the mid pipe cats and still ceramic (I’ll measure them soon) but I estimate 440cpsi like the mid pipe cats. Something like a HJS Euro 4 is going to flow better for sure, and catless better again. Going fully catless on an N54 smells terrible though I would not recommend it.