I just scrapped the original cats a couple weeks ago off my 420, the original pre-cat and full main cat, only got $152 for them at the local recycler....The replacement system was $262 or so, so it did offset a lot of it, but certainly not all. I noticed a considerable improvement in both sound and power with the single large pipe + small flow through cat setup vs. the original. As the car can hit 90-100mph on a freeway onramp, I am not complaining!

Also I went the legal and earth friendly(er) route and used a cat. Not using one is just irresponsible.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)