Join Date: Oct 2016
Location: Western Montana
Car Year: 2004
Car Model: Forester XT
Feedback Score: 0 reviews
I'm new to the forum, but I'm not new to modified Subarus. If you are running a stock 4EAT, then the ideal combination of injectors and turbo are the stock injectors and a 16G Blouch turbo. With a competent tune, this turbo will not max out the injectors, not even close (21 psi boost). Your car will feel as if there is no turbo lag whatsoever. With the gearing that it has, it will feel more like a big V8 around town. And it will be very quick indeed out to an 1/8 mile.
Along with the stock injectors and 16g turbo, however, you need some key mods to help make the tune be all that it can be. You need a 3-port Boost controller (I recommend the Grimmspeed). A 73mm big MAF tube (I recommend the KS Tech 73mm short ram with K/N filter (rather than AEM). I also recommend the AVO inlet tube (it is all one piece to the MAF tube). Invidia open bellmouth downpipe with tuning bung (do not get the divorced downpipe; the little door on the wastegate can hang up on the divider). You don't need it, but a Grimmspeed uppipe is a nice addition. Cat-back is anything that features a 3" pipe. I'm partial to Perrin (yes, the Perrin can be made to fit. Get extra-long hangers, and leave the one hanger that does not marry up empty. You don't need it. The Perrin is rock solid without it. I cut out part of the bumper and bumper insulation so that the pipe is nearly hidden under the bumper. It will not melt the bumper, and it does not discolor the bumper. It also makes the car that much more of a "sleeper."). Pull the intake manifold. It makes installing the AVO easy, and it makes it a good time to do TGV deletes (You can do them yourself. It's not hard. Buy a weldless delete kit from KS Tech.) I also put on 3mm phenolic spacers (don't know if they really do much good, but since the intake manifold is off . . . ). Naturally, you want to replace the ridiculous intercooler and the stock BOV (because it is a total misfit for any other intercooler). I recommend the Grimmspeed intercooler, and the attendant hoses for intercooler and BOV. If you can find a stock STI or WRX BOV, then they are ideal. Unfortunately, you need the goosneck on these BOVs, or you need to buy an expensive BOV, such as the one made by Cobb, that already has a gooseneck. Otherwise the hose from the inlet tube to the BOV becomes seriously problematic.
All this and, most important, a really good tune will make you a very happy camper. Some folks will claim that you don't need the big MAF tube, but if you want all you can get out of the turbo and injectors, you need this tube. We easily maxed out the stock MAF tube.
Remember: the build I'm describing above is not built around the turbo and the injectors. It is built around the transmission. It is about all the stock 4EAT can handle (assuming you drive in an intelligent, reasoned manner). If you want to drag race with it, you probably don't have more than about 25 max-power launches in it. That's just a rough guess. But launching at nearly 4,000 rpm is a real strain on the stock 4EAT. (If you want to go fast with a 4EAT, use 3-gear, especially for launches).