Originally Posted by Master2192
You have to modify the wrx turbo because it will not go below 7-9 psi of boost (Wastegate pressure). The absolute cheapest route would be to use turbo legacy parts. This will spool even faster than the WRX turbo. The usual parts list for peicing together parts from a turbo subaru is like this
-Intake and intercooler (i suggest getting a new intercooler as turbo legacys came with water-to-air intercoolers)
-Oil and Water lines for turbo
The 98RS has tiny injectors compared the the 99+ so you are going to need a RRFPR. At 5 psi of boost i'd doubt you'd need timing control, but it couldn't hurt to get something like a J&S Safeguard.
Actually, when I had my catted WRX downpipe, I was getting 5psi out of my TD04L. Also, many of the required turbo Legacy and WRX parts are the same. The deciding factor on price is how well he plays his cards. The only major difference between the Legacy and WRX is the turbo and intercooler. The WRX turbo is tiny enough and spools fast as crap on the EJ25. I have a catless HKS downpipe and I get full boost at a touch over 3k rpms. I also only spent $120 on my turbo.
On only 5psi, I suggest going the RRFPR route. Anything above that and you're better off getting an AFC or E-Manage with upgraded injectors and fuel pump. Since you have a MY99, WRX injectors will drop right in and with a WRX fuel pump, you can run 6-7 psi just fine with good tuning on an E-Manage or AFC. I have an E-Manage and RC440cc injectors/WRX fuel pump and I've been running 6-7 psi for 25k miles so far with not even a hint of detonation, ever. Compression on all 4 cylinders at 80k miles came back perfect.
BTW, with all the WRX exhaust parts, turbo, injectors, clutch, management, fuel pump, gauges and EVERYTHING, I spent less than 2,200 on my initial setup before the FMIC and a few other fun parts. It's all in the planning and frugality.
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