GTSBoy

They are unreliable cheap arse copy factory #876 Chinese crap. 4 out of every 6 are usually f**ked in the box.

Just take the head off and find out. This internet diagnosis thing is bullshit.

No. A wastegate can either stick open or closed or anything in between, plus a bunch of other unwanted behaviours. So you can either have uncontrolled boost, or barely any boost or any combination of symptoms. A BOV doesn't usually fail such that it just opens up and dumps boost. They do leak, and if it's bad enough you might lose a few pounds from the top end.

Pay that. 1992 Corolla is the only sensible choice.

There are old and new ones on eBay all the time.

Buying an NA when you really want a turbo is a bad move. Converting it to turbo is even worse.

It's on this page http://www.hypergearturbos.com/index.php?route=product/product&path=74&product_id=69&limit=100 380HP rating.

Take the rear cover off, look at the ramps in the holes in the centre casing. If the ramps are symmetric, it's a 2 way. The shape/machining of the casing, when compared to photos from google image search, will tell you if you are looking at a Nismo, or a Cusco, or a KAAZ, or one of the other options.

That's because it's not an American car. You guys like kits. We like fabricating.

If the photo of the diff is the last one above, and it is bare, not in a housing, then some decent photos of it will tell us if it is helical or not.

here

I can hear the f**ken banjos from here!

Yuh, could be sticky, could be electrically broken (ie, moves when you put power on it, but then overheats and faults, etc).

This. The viscous LSD is a piece of poo that can barely handle the power when new, let alone after 200000km.

No, don't use the Hitachi exhaust housing. That would be a baaaaad idea. Just get a dump pipe made. Buy the right flange, pay (experienced) fabricator to do a good job. Boost off into the sunset.

So you will need to Nistune the ECU anyway, because you need to be able to tune it to make it run the 25 properly anyway. That can allow you to use the blinky LED of the ECU as another output to run the VCT. Look at Nistune's support docs for how this is done. If you don't do it that way, you will need to use an EBoost or something else with a window switch to allow you to switch the VCT on and off at the required revs. The coil wiring should be all the same. You just need to google up the pinout differences on the CAS and AFM, for the most part. Oh, and injectors. I don't know for sure, but it's probably the case that you will need different plugs. Probably justified in binning the sidefeeds and using new EV14 based injectors, that you can buy with loom adapters to suit the RB20 plugs. (and a new fuel rail and the spacers and stuff you need to mount it all.)

Direct connect the boost source to the wastegate and see what happens then. Will tell you if the boost controller is good or is the cause of the problem. There are a whole lot of things that can be wrong, from problematic boost control solenoid valve, to broken linkage in the wasetgate flapper. Impossible to internet diagnose, beyond the above pointers for places to start looking.

Don't put an OP6 based highflow on an RB20. It will be laggy and you won't like it. There are smarter options. Even just the 21U based highflow would be smarter. But right now, budget considerations notwithstanding, I wouldn't choose a highflow. I'd put an EFR7163 on it. Don't buy 550cc injectors, unless they are Bosch EV14 based. If they are just old style injectors they will be shitty compared to even 1000cc EV14s. You will need a clutch (because it will not live long). You will need a diff (because it will single peg everywhere). You will probably end up needing a gearbox.

The manifold side is easy, per Josh's point 2 above. But I think the OP question is more to do with the dump pipe side. In which case, don't f**k about with cutting and shutting a new flange onto the Tomei dump if you don't already own it. If you do already own it, it might be doable. But I would just get a new dump made up.

Somewhat depends on whether you have an S1 or S2 RB25. Do you have Nistune in the ECU? Otherwise, do you have a plan for making the VCT work? The main points are: Dealing with pin changes on the AFM and CAS. Differences in connectors for things like the alternator (and AC compressor, if that matters to you, which it probably doesn't). Ignitor pack/coils, which is where the S1/S@ thing comes in. Probably best you give a little more info on the type of 25. I'm not saying I've got the answers, but others might be better able to point you to the howto you want.

That is f**king smashing! That has to be the street turbo of choice.

No. Surely not!

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I've done it myself using my mechanic's generic scan tool (ie, workshop quality, just not a Nissan Consult only unit). How do you think workshops diagnose this stuff?

They do. You can use ANY decent scan tool to pull the fault codes out of ALL the CUs in the car. That's ECU, TCU, ABS/TCS and HICAS. There are even procedures* for putting those CUs into diagnostic modes and the idiot light on the dash will blink the codes at you. *that involve turning around three times with you hand on your head, shouting "Wiggle wiggle wiggle" and doing 5 star jumps while reversing slowly at <1 km/h.