Unless i'm mistaken a RS uses a MAP sensor not a MAF sensor.

I had rumor that a MAF sensor was used in the 05 but i haven't looked it up to confirm.

3k sounds a lil high on the tach for 70mph but it probably has all around 4.111 ratios in the diffs.

 

The 98/99 RS uses a MAF. The 00-04 uses a MAP. They went back to MAF's this year for the 05's though.

 

No MAF in your car probably as Kostamojen said.

The revs are normal.

Turbo on that motor isn't worth it unless you can afford to suddenly have to rebuild your motor at some point. It's a serious risk.

 

Or you can rebuild it now so it can withstand the turbo pressure. Like forged piston with lower compression ratio, piston rod, stronger cylinder (thicker), better intake, better header, and all the other things in the BJ25 that lacks the strength. BJ25 was built so precise that its not good for turbo tuning. But if you change all those things that are weak in strength to match your turbo, you got yourself a semi-STi.

 

The negative parts of the EJ25 in the RS run deeper than jsut tolerances. That has nothing to do with it. But swapping in an EJ20 or STi EJ257 is less expensive and WAY easier than rebuilding the stock motor from scratch.

 

There's more to it than that, but the open deck part is true. The STi internals (rods, pistons) are also much stronger. More importantly, the compression is lower making it a boost-friendly engine.

 

Isnt that what I've said in my post before?? Stronger Rods so it wont blow up when psi is higher than 8lb. Forged Pistons to make the compression ratio lower to allow more space for the turbo. Thats what I've been saying and you denied my answer.

But its true, with all those things to strengthen the EJ25 motor, it will cost you $5000. For that price, i would suggest you to do a motor swap to a EJ25T. It would be easier and less risky than doing a full internal modding for EJ25. You will have money left over to get a factory (or aftermarket) STi hood and a STi badge for your trunk =)

Final conclusion, dont bother with the internal mods for your RS, change it to a STi

 

A complete swap means absolutely everything from intake to muffler, plus ECU and wiring. You'd also need a turbo crossmember and a stronger transmission. You can get a JDM v7 or v8 motor for around $5000, give or take depending on specifics of the motor and where you get it. Figure $1500-2000 for installation.