I finally got my catback... 2.5" mandrel bent, tig welded with a borla exhaust... and I lost 10 hp up top! So I look under the car, and find they have replaced my 2.5" cat with what looks to be a 2", but I'm not positive. Could this account for a loss of 10 hp up top and nearly 20 hp in the midrange? My tuner also thinks the exhaust exit is only 2-1/4". (My previous pull, with all the mods except the exhaust, netted 188.3, I'm now at 178.)

Mods:
Skunk 2 Stage 1
tuned Hondata s200
jdm dc 4-1
aem cai
custom exhaust

 

well, dyno the same car on the same dyno, on different days and you will probably see some variance.

And what do you mean you "look under the car and find..." Didnt you KNOW what they were putting on your car??????

I recently put a full 2.5inch b pipe on my car, with Carsound cat and stock muffler. Not much difference at all, other than a lot of noise. Put your stock exhaust back on and hit up the dyno again and see if you gain any power back. The stock exhaust isnt really that bad for a mild set up, Im at over 200whp on the stock exhaust. Quiet ownz.

 

i understand some variance, but 20 hp midrange? i mean, ouch...

I knew what they were doing the with the exhaust, then the guy calls me and tells me that I should get a new cat, that my current one is too small... Being an idiot, I believe the guy, and tell him go ahead, but they give me a smaller cat instead...

 

Sounds like something else is going on...althought the cat converter story sounds fishy as well...

 

i looked at the piping, it's all 2.5", and the bends/welds all look pretty good... so I'm thinking it's the muffler/ cat that really screwed it up... just wondering if going from a 2.5" cat to 2" could do that much hurt to the power?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jiahanhao &raquo;</TD></TR><TR><TD CLASS="quote">... just wondering if going from a 2.5" cat to 2" could do that much hurt to the power?</TD></TR></TABLE>

How did they even mate a 2" cat to a 2.5" collector?

 

and by "borla exhaust", Im assuming you mean the muffler section? why did you go with that??

sounds like you should have done a lot more research before going through with this.

 

they used a pipe reducer to fit a 2.5" flange onto the smaller inlets of the cat... i'll have pictures in a moment

 

Maybe they sold you a screwed up cat. My bro-in-law's cat was completely melted at one time, after he took it off and made the innards of the cat outterds it gained all sorts of horsepower at the expense of being legal.

The point of the story, is it a brand new cat?

 

i hope so.. here's the pics of the cat mated to header





my old cat was definitely 2.5", and they reused the flanges from it, anyone want to tell me what size they think this cat is?

 

dude my **** is thicker than the piping on that cat. it looks to be about 2'' piping

 

what cat is that? the flange looks like its 2.5", the "adapter" piece is maybe 2" and the cat outlet is like 1.5" LOL

you should go back there and raise hell!! I never would left my car there for them to work on a "custom" setup with out being there, and I certainly wouldnt have driven away with the exhaust like that.

 

these pics look like nasa pics taken in space... measure OD diameter of both.

 

O.D of piping.... flange -&gt; 2.8", adapter pipe -&gt; 2.41", cat inlet -&gt; 2.10"

 

did you tune the a/f ratio? add any fuel?
if you didn't then it's obvious why you lost hp.

 

it's been tuned already, tuner told me the exhaust should not significantly affect the a-f ratio, but we'll see once i get the bigger cat back in...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jiahanhao &raquo;</TD></TR><TR><TD CLASS="quote">




</TD></TR></TABLE>

That is one ghetto *** job.