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Discussion Starter #1
Hey guys, new to the forum. I have an is300 03 auto. I have a small list of parts I’m planning to buy and I want to make sure that the parts I’m getting is all I need and I’m not missing anything important.

Cxracing kit 8 psi
Gte headgasket to lower compression
Greddy exhaust catback
Maybe 500cc injectors? Idk if i need them. You guys tell me
255 Walbro fuel pump
Emanage ecu idk ab ecu stuff but this looks like a good option. Still not sure

Do you guys think this is all I need or am I missing a lot of stuff. My goal is around 300rwhp+ this is gonna be my daily driver it has 80,000 miles on the motor.
 

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No reason for the GTE headgasket really, especially at 300whp. I would also recommend talking to whoever is going to tune your car and what they are comfortable with. It wont make a difference if one ecu is "better" than another, If your tuner doesn't like it, you're going to have a bad time.

the CX racing kit will be fine for a low boost daily, I just wouldn't trust its parts (outside of the IC and piping) going over the 8-10psi range. I am sure some people have been fine with doing more, but relying on those turbos/wastegates/bov's to be a reliable daily isn't worth the risk IMO.

Edit: You'll want the bigger injectors. 565cc WRX STI injectors are a budget friendly drop-in option. You begin to run out of fuel quickly on our stock injectors.
 

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Discussion Starter #4
Thebigchow

Thanks for your answers! You sure I won’t need the gte headgasket? Because the is300 has 10:1 compression and with a turbo it’s going to be add more pressure. I’m not sure of the limits of the ge headgasket.

What would you reccomend for a turbo and wastegate?

And as for transmission, I’m gonna shim the gears or springs idrk what it is but I’ve seen a videos of people shimming the gear springs so there is a bigger gap and supposedly that is supposed to help the transimission handle the power better and shift harder
 

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Thanks for your answers! You sure I won’t need the gte headgasket? Because the is300 has 10:1 compression and with a turbo it’s going to be add more pressure. I’m not sure of the limits of the ge headgasket.

What would you reccomend for a turbo and wastegate?

And as for transmission, I’m gonna shim the gears or springs idrk what it is but I’ve seen a videos of people shimming the gear springs so there is a bigger gap and supposedly that is supposed to help the transimission handle the power better and shift harder
You will need around a 62 mm turbo or a little bit bigger. I have seen the numbers you are after. Around that. I would do some reading on the forum. A few have done this.
 

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Do you recommend any specific turbos I should consider?
The biggest thing with any turbo. Is to match the AR rating with the range you want. The size only helps dictate the power. If your AR is to big on the exhaust side it will not spin up when you need or not get to the boost range you want. They are all good and bad. Just ask anyone. They all have favorites and bad stories.
 

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You will need around a 62 mm turbo or a little bit bigger. I have seen the numbers you are after. Around that. I would do some reading on the forum. A few have done this.
I'd say that considerably more than a few....every time one of these car changes hands the question gets asked, a thread gets created. Thats a lot for an 18 year old car.
 

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Discussion Starter #9
Do you recommend any specific turbos I should consider?
The biggest thing with any turbo. Is to match the AR rating with the range you want. The size only helps dictate the power. If your AR is to big on the exhaust side it will not spin up when you need or not get to the boost range you want. They are all good and bad. Just ask anyone. They all have favorites and bad stories.
Thanks for your input. I didn’t know About AR ratings. I’m new to the turbo game so thanks a lot. Btw I’m ab 1 hour and a half from Marietta
 

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Thanks for your answers! You sure I won’t need the gte headgasket? Because the is300 has 10:1 compression and with a turbo it’s going to be add more pressure. I’m not sure of the limits of the ge headgasket.

What would you reccomend for a turbo and wastegate?

And as for transmission, I’m gonna shim the gears or springs idrk what it is but I’ve seen a videos of people shimming the gear springs so there is a bigger gap and supposedly that is supposed to help the transimission handle the power better and shift harder
There are guys putting out some “big” power on ge headgaskets, with a quality tune the compression ratio is fine. If later on you want more power, the gte pistons will lower the compression, that with a new ge head gasket, arp head studs and you have a nice set up. I know a few around the 600whp on that kind of setup.

For wastegate’s Tial, HKS, Greddy, are all good choices

Valve body upgrades and throwing on a trans cooler should be enough if the trans has been well maintained.
 
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