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secondary cat bypass

3K views 13 replies 9 participants last post by  rdl 
#1 ·
Hi

Looking for opinions on secondary cat bypass pipes. Eisenmann and Supersprint both make them.

Any noticeable differernce in terms of:

power
torque
throttle response
sound
smell of exhaust fumes

Thanks.
 
#2 ·
jus go to ur local muffler shop and tr8 pipe it.
 
#3 · (Edited)
xpipe

i would go with the SS x pipe first so see how it sound then go for the secondary cat bypass......i would use the eisenmann if u have an eisenmann exhaust but if u have supersprint then go with supersprint's bypass. I think the eisenman sounds deeper.....u will feel better throttle respond and good gain with both.
 
#4 ·
Based on most dynos out there it seems that the primary
cats are the bottle neck. Get rid of those and you'll see
the most hp/tq gains. Removing secondary cats and resonator
gives minimal gains but makes things louder. I'd say if you do
it, do it for the sound and not the performance.
 
#6 · (Edited)
There is package from Turner Motorsport that deletes the pre cats, exchanges the stock secondary cats for race ones and ECU tuning. This retains the stock headers, reduces cost and gives nearly the gain people are getting with headers. So it must not be too tough to remove the precats and retain the headers.
I'd be curious to hear it with the stock rear exhaust.
Marshall's right though performance gains for both x-pipe and cat delete are small.
I think the secondary cat delete will give you a little more performance than x pipe and a little more volume. The tone is probably the biggest difference between the two. Sound is so subjective but my take is the x-pipe will be more growly and the cat delete will less of a change in tone but maybe more wail at WOT.
 
#8 ·
Yeah, headers are a pretty intense mod. The Turner approach
does lop off the cats from the headers + high-flow secondary
cats. At 6.5k w/o labor I think it's ridiculously overpriced.
Not only that you alter your oem headers. Not good if you
ever need to go back to stock.

Anyways...good luck and please post pre and post dynos if
possible.
 
#10 · (Edited)
Me too. Supposedly the pre cats are the most restrictive segment. The Turner package is pretty expensive. The main expense is from the race cats. I would like to know the cost and performance gain if the stock secondary cats were kept instead of race ones. Probably a lot cheaper and only a little less gain.
Terence,
Good luck and post back with impressions and hopefully even a sound/video clip
 
#13 · (Edited)
Any news on this? Has anyone heard of someone keeping stock headers and just replacing the pre-cats? I know evosport is now offering cat delete pipes for less than $500. Any numbers or any idea how this will increase performance? Thanks
 
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