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MP Performance 3" Downpipe Produces 10-15 HP Gains

4K views 25 replies 13 participants last post by  ERP  
#1 ·
This week we finished production on our 3" stainless steel downpipes. And today we took it to the dyno. I knew the downpipe would produce an increase in power, but I was surprised by the amount of gains on a stock 9-3. Across the entire rpm range the 3" downpipe showed at 10-15 hp improvement. Spool up was noticeably quicker and top end power did not fade as much. The stock 9-3 being tested produced a peak of 175 hp and 193 ft-lbs torque at the wheels. With just the downpipe, performance shot up to 186 hp and 206 ft-lbs torque. This data illustrates the large restriction that the stock downpipe produces.

We are now selling these stainless steel downpipes on our site for much less than any of the other competitors.

www.mpperformance.com

Eric
MP Performance, LLC

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#3 ·
Awesome Job guys, it’s finally good to see a company backing up their performance mods with a Dyno. Nice Results
 
#5 ·
No this was on a test car...erics car is a T5 but is running a catted JT.

I have a 95 with no cat, so I dont have engine light issues. Blaq is running a 96 with no cat, and is getting a cel.
 
#8 ·
I have a NG900 with JT no cat and i have no CEL, my car is 1998.
 
#13 ·
that's not a bad price for stainless.., but the downpipe and race cat made me a believer...on my 97 NG900.

I put my downpipe and race cat on with my first IC changeout. So the difference in power was a lot more noticeable for me since I replaced that dual pass IC I had with a one pass type.

Bought an analyzer for the CEL's and the error corresponds to faster exhaust on the primary O2 sensor....at least that's what my computer told me when I plugged in the results. I then realized I need to pipe the entire exhaust back using a 3 inch pipe, and it cured the CEL's.

Analysis shows the older 2.5 exhaust I had created some nice back pressure, but slowed the exhaust flow for the secondary O2 sensor.

I can only speak for my car...and not sure about the other models, but any chance those of you are running a complete 3 inch all the way back had no CEL's...as opposed to a 2.5 inch cat back, that did?

hope this helps...

regards
 
#15 ·
Hey DC, i'm running full 3inch all the way through, this could be the reason why i get no CEL. But also i know Cedric is runing the same setup as me but i only have one muffler and he has two. So who knows what it is.

Also Eric i would like to know also if these results were with a Cat or not.
 
#16 ·
Thanks for all the responses.

The Saab used for the test was a 2000 base 9-3, T7, rated at 185 hp stock. The high stock wheel hp is consistent with some of the later model 9-3’s. Saab seems to have upped the horsepower without changing the listed specs.

As others have mentioned any 1996 Saab or later should throw a check engine light if the catalytic converter has been removed. It takes at least a few dozen miles for the CEL to illuminate but it doesn’t always come on. The CEL light is more likely to come on during normal cruising than when pushing it hard. To be safe I would say that you should assume your 1996 or later Saab will throw a CEL if you install a catless downpipe. However there are ways around this, I’ve seen people install 02 simulators to keep the second 02 from throwing a CEL.

We are planning having the 3” downpipe with a catalytic converter dynod shortly, and I will post the results when we get them. Right now the high-flow cats are on back order, but we are expecting them any day.

Eric
 
#18 ·
Let's make sure we're looking at apples and apples here:

Eric, are those dyno comparisons between a stock 9-3 WITH cat, and a 9-3 with NO cat and 3" downpipe?

If so, then how much of that HP gain is simply the elimination of the catalytic converter from the exhaust flow? I think you'd need to run yours with a cat to get an accurate gain figure, and that would give a good baseline benefit number for most folks whose states require cats.....
 
#19 ·
LOL no way a t7 gaining hp.. who woulda thought... alright well if those stock hp figures are correct then that makes a lot of sense y my dyno numbers were so high as well... thats awesome.. so with a dp and a cat i should gain maybe 8-9whp... thats great... then again those figures would b on a stock 9-3 so i may gain even more... sweet.... maybe i just wont get software at all.. considering how well my car runs on stock sw
 
#20 ·
mike saunders said:
Eric, are those dyno comparisons between a stock 9-3 WITH cat, and a 9-3 with NO cat and 3" downpipe?

I think you'd need to run yours with a cat to get an accurate gain figure, and that would give a good baseline benefit number for most folks whose states require cats.....
Yes to the first question. And we will dyno a 3" downpipe with 3" cat as soon as the cats come in. Should have the results some time mid next week.

Eric