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Under pressure
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9 Posts
Discussion Starter #1
Hey everyone...

i'm new here, and looking for some advice. I'm looking for an exhaust system (doesn't need to be cat back, MI doesn't inspect or do emissions) for my sonoma. It's a 98 SLS with a powerdyne on it. I want to hear your horror stories, as well as what works for you guys!

Thanks!
 

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Trick MotorSports!
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1,253 Posts
What PSI you running....with the 10psi ATI kits, a custom 2.5" y-pipe and 3" cat back works the best.
 

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Ground Force Truck Club
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31 Posts
if you are blwon, the bigger the pipe the better, remember the point of the charger is to push air in as fast as possible, so in order to get it out as fast as possible, you want a nice big exhaust and some nice big headers :D
 

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Under pressure
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9 Posts
Discussion Starter #4
yeah...thanks... i knew that! ;) but i was looking for some specific reccomendations, i.e. brands and models that worked for you. i had a supercharged mustang, so i am intimately familiar with the ins and outs of supercharged vehicles. just looking for testimonials :) besides, bigger is not always better! it's finding the right size to get the right amount of backpressure and good scavenging.
 

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Yeah, still on the bottle
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201 Posts
Spin-Tech exhuast or Random Technologies... good stuff
 
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768 Posts
Well, I've got the 7 psi Powerdyne (soon to be a 9 psi Powerdyne, LOL) and I am running JBA headers, the SLP y-pipe, a Dynomax 13.25 Super Converter, and the 2.5" Dynomax Ultra-Flow cat-back kit.

Why so simple, you may ask? Well, contrary to popular belief, these newer engines don't work like the older hi-po engines -- they require backpressure to fully utilize what they're getting. If you open up the exhaust too much you LOSE power (i.e. you may have a gross gain of 30 rwhp, but because it flows too freely you lose 10 rwhp elsewhere -- not to mention the torque you lose, so you actually only have a net gain of 20 rwhp). If your exhaust escapes too quickly there is no time for the motor to build up the high combustion it needs (especially in a forced-induction set-up). Therefore, while 3" true-duals all the way back may work relatively well for N/A applications, it is not as good for forced-inductions. Also, if you free it up too much you will lose rw torque as well -- which we all know is directly related to acceleration. So, you need to keep some of that back-pressure bottled up (but not too much, obviously). Also, if you free up exhaust flow too much you run the risk of damaging your heads (or head gaskets) and fouling your plugs more quickly. Also, I noticed a mention of an X-pipe -- that is not a good idea for forced induction -- it works absolute miracles for N/A, but supercharging is a realm of its own and a lot of rules don't apply (of course, a lot of us make up new ones as we go!).
 
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768 Posts
To give you an idea, here's my mods:

4.3L V6/NV3500 5-speed manual transmission

K&N cone filter and "first-stage" induction tube from FIPK II
Granatelli MAF-sensor
Casper TPS-TEC
Powerdyne 7 psi S/C
MSD 6BTM ignition
MSD Superconductor plug wires
Hypertech PPIII (speed limiter ONLY -- other settings can kill S/C motors)
JBA Headers
SLP y-pipe
Dynomax 13.25" Super Converter
Dynomax 2.5" Ultra-flow cat-back kit

Future mods (some in progress):
Richmond 3.73 gears
Centerforce Dual-friction clutch
Titanium stabilizer bars (front/rear)
9 psi (2.70") pulley for S/C
Custom Intercooler -- I'm still working on the design -- Mach says his will just cut the boost too much on the Powerdyne, so I'm trying to overcome the boost loss -- I've got an idea or three, but the "ironing-out" process is taking a little bit (between work, play, family, etc.)
Possibly a T56 (6-speed trans) swap
 
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768 Posts
Oh, BTW: don't ask me my dyno numbers -- I haven't had the chance yet, but I am going to be attempting to do so this Saturday (June 8th) to see where I stand. . . Wish me luck.

I haven't gotten to the track yet either (moving and renovating a house can be EXTREMELY time consuming) but that will be changing soon!
 
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768 Posts
Oops, I forgot a mod on my list. . . Sorry. . . I've also got a Flex-a-lite Black Magic #60 electric fan. . . I may have forgotten another mod or two. . . I'm sure I'll remember -- eventually.
 
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