Hi Flow Cats/tune

uvbnbit

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I'm going to order some Hi Flow Cats this weekend and leaning towards Seans.
I have 6.5 Roe, Vec3, 1.7 HS's, 1 5/8" B & B 's w/3" catless out the back now.

Will adding hi-flows require any change in tune?
Also,
I've had the rear O2's zip-******* out of the way for 6 yrs now (no codes :D). should I replace them and stick back in pipe or just leave 'em tied out of the way? or ? ? ? ?

Thoughts/ suggestions /
 

plumcrazy

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shouldnt but if its been a while since you tuned it, it might be a good idea to double check it
 

uvbnbit

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I'm not expecting a huge loss/gain, but was just curious. I'd hate to leave some HP/TRQ on the table without optimizing it.

I've got about 4 yrs on current upstream O2's and plan on replacing them too.
Does anyone sell the O2's with longer wiring to reach the header collectors so I won't have to splice in a foot of wiring again?
 

ViperTony

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PM sent. Also, I have O2 Wire extension harnesses you can have Chip. They're from Casper Electronics, part #109034 and can be used in between the O2 wire harness and sensor without splicing. I bought them in '10 but don't need them.
 

uvbnbit

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I finally got my Hi-flow cats installed, (installed new O2's also and reset PCM) and went on a 20 mile ride.....so far, so good.

Observations:
-more heat, but not as bad as stock...of course.
-no exhaust smell, no clothes wreaking of unburnt fuel....YES!
-I do smell a "metallic" odor, like a struck match. assuming it's just the initial warming up of cats and may be less as driven more?
-WOT a/f was in the 11.2-11.5 range.
-I threw a CEL and cant remember code, but it was "MAP voltage low". I think on my 3-4 shift, I just had too much vaccuum and manifold pressure sensor didn't care too much for it.
-cruising speed was a bit quiter, as well as my 2200-2700 "noise/drone" is gone...another
-a deeper/smoother exhaust tone.
-we pleased with our decision.

Thanks for all the replies.
And special thanks to ViperTony for mailing his sensor extensions to The Wizard who spliced in the extra wire to my O2's.
-chip
 

charlesj

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-I do smell a "metallic" odor, like a struck match. assuming it's just the initial warming up of cats and may be less as driven more?

I know exactly what you mean... For me, the smell just went away after awhile. This is also a general rule of life. Life Rule #256: Handling Unusual Smells. Ignore them and see if they go away. If they don't go away or get worse, than consider investigating. :)
 
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