I have a sorta-bud in the motorsports biz who has a dyno in his shop.
I've never asked him for time, but when we were chatting about the no-cat thing he mentoned that he wanted to "explore" this further, with possible new services and knowledge gathering for his customers in mind. I got some free time!
I found a set of exhausts in a scrap yard ... removed the cats and had the system converted to straight throughs (along with some general patchin 'n fixin).
With the original system in place we did a quick run. Then I switched out the the systems and back the next day.
Whoohaaa! I picked up 28hp at the wheels. Torque is up about 19lbs. It's now at 347 @ wheels with just a chip and no cats. Total cost about 260usd. Watching over the last few days I also gained about 2mpg .. except that the engine is soooo much more responsive - attentive to throttle - that it will be difficult to drive normal. I need to get some 0-60 times ... except that I never got a before 0-60 ... so this might be a useless activity. However, it is obviously quicker ... revs building a lot faster than they used to. I should have base-lined this car right after I bought it.
Plus you should hear this thing ... sounds like a V8. It's not quiet anymore, especially at WOT. I think I'll insert a couple of Cherry Bombs in the flow somewhere to hush up a bit. Should have put them where the cats were .. oh well.
I think I'm done with perf changes here ... this car is scary-fast enough. It's track-day time!

95 540ia
93 318is -270k!
90 Civic Si DOHC ZC
96 Rav4 - WINTER BEATER! no really -

• New twist to 'green' motors, requires a question: - e34jef 2008-05-16 19:16:48 (134 views)
  • No cat update: - e34jef 2008-05-21 08:01:02 (94 views)
    • Without an ECU Update . . . . - rlomba8204 2008-05-30 16:01:11 (38 views)
      • No EGR, at least not in my particular car - dave535i 2008-06-01 09:43:03 (39 views)
        • Internal EGR - kfister 2008-06-01 20:25:30 (33 views)
    • Wow - kfister 2008-05-21 09:45:14 (57 views)
      • Wolf and a Dinan in the ATrans ECU. (nt) - e34jef 2008-05-21 17:32:41 (68 views)
        • BTW Ken ..... - e34jef 2008-05-21 17:43:30 (64 views)
          • I actually bought a CO-alarm from the home warehouse for the garage - kfister 2008-05-23 07:52:27 (57 views)
  • Might not be worth it.. Also your OE cats are worth much more - kfister 2008-05-17 15:42:28 (72 views)
  • HA! No Emissions...I live in California!! 76 down..are exempt (nt) - louiseven 2008-05-16 23:30:07 (64 views)
  • Re: New twist to 'green' motors, requires a question: - yaofeng 2008-05-16 20:41:54 (73 views)
    • Re: New twist to 'green' motors, requires a question: - rick540 2008-05-18 07:19:15 (65 views)
      • i don't like either of them!! anyway(well maybe a range rover sport) (nt) - explodingbudgie 2008-05-22 02:28:27 (52 views)
        • Exact opposite for emissions in California!!! - spyjunior 2008-05-29 19:56:25 (39 views)