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Discussion Starter #1
well i have a sti and this car needs to just be a tad faster, have some questions seeing if you guys have answers

1) is there a smaller pully you can put on the supercharger. bring boost up to 10 psi i dont mind mixing race gas in the tank to avoid detonation.
2) i was planning to do a single 3 inch exhaust from exhaust manifolds back with no cat. or would 2.5 pipe be better
3) does anyone sell a complete exhaust manifold back set up
4) Does anyone make headers for the car
5) cold air intake anyone
6) computer set up

way i see it car is 205 now. if i can get 10 psi i can get extra 40 easy there, exhaust with no cat 3 inch from the exhaust manifolds prob 20 wiht no cat, headers 15 hp, air intake 10hp, computer like hypertech prob 20 hp.

any help woulbe appreciated.
 

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First never run it without a cat. Unless your a full race car you will have very small benifits of not having one. Get a hi flo cat 3" inlet and out. Cats have come along way in the last few years and the HP loss is not worth the dammage to the enviroment. Not that I'm a tree hugger, but come on their there for a reason.and it is possible to crack your exhaust manifold and valves by cooling them too fast. the converter holds a bit of heat and keeps the air from out side from cooling them too fast. Also choose a good wheel. find out what the stock rims weigh. then get some aftermarket wheels that weigh a few pounds less. 1LB of rotating weight is like 10LB of static weight. So if you can shave 2LB per wheel thats like 80LB of interior weight.... and it will handle quicker...
 

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for 1 or 2 hp it isnt worth getting popped for having no cats. around here, no cats will set you back $1000 for your first offence, and you win a no-expense paid trip to the smog referee. that means that you will have to pay to put it all back to stock inorder to pass! thats a whole heck of a lot of money for a handful of horses. heck even 10hp isnt worth that cost! there will be lots of ways to make real power, just be patient.

i bought one of the first SRT4's in teh market. and it took a while for parts to come out, a long while. but now that its been a year or 2, there are a TON of parts floating around. just be patient and you will be able to go as fast as you could ever want too
 

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Discussion Starter #5
on my sti 3 inch dp with 3 inch highflow cat i had 8 less hp at wheels than without the cat

well ill prob have sanderson headers out here do a 3 inch header back set up for me this week see how that works out
 

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NORCALSTI said:
on my sti 3 inch dp with 3 inch highflow cat i had 8 less hp at wheels than without the cat

well ill prob have sanderson headers out here do a 3 inch header back set up for me this week see how that works out
So you have a Cobalt SS? Or do you drive an Sti or is it both?
 

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NORCALSTI said:
well i have a sti and this car needs to just be a tad faster, have some questions seeing if you guys have answers

1) is there a smaller pully you can put on the supercharger. bring boost up to 10 psi i dont mind mixing race gas in the tank to avoid detonation.
2) i was planning to do a single 3 inch exhaust from exhaust manifolds back with no cat. or would 2.5 pipe be better
3) does anyone sell a complete exhaust manifold back set up
4) Does anyone make headers for the car
5) cold air intake anyone
6) computer set up

way i see it car is 205 now. if i can get 10 psi i can get extra 40 easy there, exhaust with no cat 3 inch from the exhaust manifolds prob 20 wiht no cat, headers 15 hp, air intake 10hp, computer like hypertech prob 20 hp.

any help woulbe appreciated.

The STi is rated at 300Hp is it not, secondly its turbocharged not supercharged thus there is no pulley. You only have one header as its a 4 cylinder, and with the smaller engine 3" may be a bit big as one person said.

Unless you have an SS cobalt which is a different car.
 

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Ok so I'm not the only one htat got confused by his post, judging from his other thread I think he has an Sti and now bought a cobalt SS and is looking to make it faster?
 

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negitive my colbalt friends. 3" is the ideal set up on a 4 banger turbo. thinkn of the standard for V8 cars..... 4 cylenders per side with dual exhaust....on a standard 350 5.7L chevy you get a 2" 3/4 for a good hi po motor. NOT forced induction... thats 2.85L per side now force feed it and a 3" almost seems small. but in the real world with the price of larger pipe and the nessary room to put that big of a pipe under a car and still get over a speed bump a 3" is the perfice size. i worked great for years on a 2.2L 20psi daytona shelby.....
 

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cobaltssblue said:
negitive my colbalt friends. 3" is the ideal set up on a 4 banger turbo. thinkn of the standard for V8 cars..... 4 cylenders per side with dual exhaust....on a standard 350 5.7L chevy you get a 2" 3/4 for a good hi po motor. NOT forced induction... thats 2.85L per side now force feed it and a 3" almost seems small. but in the real world with the price of larger pipe and the nessary room to put that big of a pipe under a car and still get over a speed bump a 3" is the perfice size. i worked great for years on a 2.2L 20psi daytona shelby.....
Well it actually depeds on the hp you'll be putting down, we dynoyed our 92 Daytona with the super 60 turbo at 212WHP with a 2.5inch exhaust, then we put in a 3inch and the power never changed. On our 86 Shelby charger with a t3/t4 hybrid though the car picked up 8who going from a 2.5 to 3inch exhaust but the car was alreay making 300WHP+
 

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Pablo said:
Well it actually depeds on the hp you'll be putting down, we dynoyed our 92 Daytona with the super 60 turbo at 212WHP with a 2.5inch exhaust, then we put in a 3inch and the power never changed. On our 86 Shelby charger with a t3/t4 hybrid though the car picked up 8who going from a 2.5 to 3inch exhaust but the car was alreay making 300WHP+
Agreed, 3" is not always the ideal set up. Exhaust is often made to big for the car, and you also need to remember that a supercharger acts differently with exhaust than a turbo does, on a turboed car the exhaust already has backpreassure in it so there free'er flowing the better, but on a SC car going to large can cost you power. It also depends on if you have dual or single exhaust.

I would say plan for your long term goals, if your going to make a 300+ HP car then go 3" as its probably going to be significantly modded, but if you just want the car a bit quicker, say into the 13's, then I think 2.5 or 2.75 would be better.
 

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Backpressure in your exhaust system is _never_ good, under any circumstances.

N/A
Turbocharger
Supercharged

Doesnt matter... your engine is an air pump. More air in + more air out == more power. Period.
 

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ekool said:
Backpressure in your exhaust system is _never_ good, under any circumstances.

N/A
Turbocharger
Supercharged

Doesnt matter... your engine is an air pump. More air in + more air out == more power. Period.
True, but going to large can cost you power, as the exhaust leaves the engine the temperature cools significantly, and the exhaust then expands and slows down. This slower moving exhaust can cause backpreassure on the exhaust as it exits the pipes. This can be solved by going with smaller pipes the farther back from the engine you go. For example, you can go with a 3" primary, to a 2.75" intermediate pipe, to 2.5" cat back. This way the cooling exhaust can't expand as much and doesn't cool down as fast, thus keeping the exhaust free'er flowing.

Backpreassure gives you torque, so a little isn't a bad thing. Thats not saying you should go stick in non mandrel bent pipes or more cats or anything.
 

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Discussion Starter #15
i was thinking
pulley
slicks
ecu
cold air intake
nx 50 shot
header and full exhaust

that should get me into 12s with the jug im thinkin
 

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NORCALSTI said:
i was thinking
pulley
slicks
ecu
cold air intake
nx 50 shot
header and full exhaust

that should get me into 12s with the jug im thinkin
Tat should make for a hella lot of fun, should be good for 110+trap sppeds.
 

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I'm not big into voiding my warranty but hopefully GM performance parts will be able to supply everything I need...ideally I want to do:

Whatever Stage systems they offer which should include a smaller pully, ECU reflash, etc.
Headers without a doubt
Possibly Cat-back exhaust
Cams
CAI
and maybe some lighter wheels with better grip down the line. If GM offers a stage increase for another 70hp at the wheels I think I'll be good. But if GM is listening MORE IS BETTER!
 

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Stupid question, anyone on here actually have one of these things and taken it too the track,? dyno anything? I really don't see it being a huge assualt on alot of cars, maybe the SRT4, but the STI and EVO i dought.
 

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spooldyou said:
Stupid question, anyone on here actually have one of these things and taken it too the track,? dyno anything? I really don't see it being a huge assualt on alot of cars, maybe the SRT4, but the STI and EVO i dought.
It isn't meant to compete with those cars, its meant to compete with the SRT4 and SVT focus. The car would be competitive if you dont factor in the AWD.
 
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