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Discussion Starter #1
Before you answer that, keep in mind I'm in California, home of the emissions nazis. You can't even order a boost controller here anymore, Amazon/UPS/USPS will not even route it here. I'd have to order it to my stepdad or sister in Arizona and they covertly mail it here. And then...not being mechanically inclined, I'd have to find someone willing to risk their mechanics or business license to install it. Not gonna happen. And if I got any mods done out of state, I may have to license the car in that adjacent state because smog shops have the right in this state to literally rip out mods permanently if they see them and they are not CARB approved. Not to mention them failing the car and me driving around with expired tags. This happened to my last controller, solenoid thrown in trash by smog station, wires torn out. And forget trying to do an EGR/vacuum hose delete...in this state, same issues as above.

For my emissions situation and lack of skills/tools/jack stand, etc., it seems like pinching the wastegate hoses is far easier. If I floor the throttle and it shoots way up past 14 psi, like it used to do, I can always let off the gas a bit or simply upshift. It was not too hard to locate the front wastegate and hose going from that to the center of the engine, but the rear, I can't even see the wastegate or turbo from the top of the engine. I'm guessing on the hose. Can take pictures if needed. The dealership mechanic routed two different T's instead of the typical H joint. And that's OK, it boosts to around 12 psi for now on a 98' model, but I really miss it going up to 16 or a bit more. Stock fuel pump handled that just fine. I think I found the rear wastegate hose, it goes off the 1st (right-hand) T to the right, down towards the back-center of the engine bay, originally from the boost control solenoid before it hit the first T. That seems like the only possible hose that is correct.

Now the question is how to clamp such a small pair of hoses. Right now just as a test I'm trying paperclip binders and will see if that gets the boost up to 14 or not. Maybe I can live with 14, 16 is nicer of course! Remember that if you reply to this, I'm really, really limited in my options on how to increase boost, both by my state's emissions laws and by my lack of skills/tools. A lot of people have said in the past "Oh, just take this out, put this in, wrench that out, replace this", but they assume I have mechanic skills and I don't. They left out 90% of the details needed by someone who doesn't exactly do this every week! However, if someone had a really nice, detailed, step-by-step instruction protocol for a boost control install, I may try that. It would have to have every single step, every step, even the 'obvious' ones.
 

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Typically people just add T's to wastegate vacuum lines as the 'ghetto' way to increase boost since it bleeds off some of the air before it reaches the wastegate (same as operation of some MBCs). I guess clamping could also work? Just not sure if it would be more inconsistent. I would be weary of anything like that where you can get huge boost spikes before you even notice. Also, if you don't have anything aftermarket added, how are you measuring boost? OEM gauge? Because that is not accurate.

Honestly i would just install a MBC and hide it. There are some where you can route the vacuum lines easily out of sight in the engine bay or even into the cabin, and if you are really worried about the visual inspection, swap them back to original before bienneal smog. Were talking about maybe 30 minutes of work every 2 years.

Having said all that my recommended approach is find a better place to do your smog checks. I live in CA and have driven catless with basically all emission controls removed and almost nothing in my engine bay original for 12 years. Not all shops are 'emissions nazis' as you put it. You just need to find the right ones. Its very easy to find shops that overlook visual if you pass sniffer test. Finding shops that pass the sniffer test is another story if you are catless. Honestly i wouldnt even drive my 3000gt anymore if i had to retain it in stock form.
 

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You have to be smart about how you hide your mods in a nanny state... Most smog techs have no clue on these cars, and would really have to know what they were looking at to find any well hidden mods. Larger turbo wheels in stock housings will go entirely undetected, larger fuel injectors will never be noticed provided they don't have big advertising labels wrapped around them, tuning and boost control can all be done with a programmable ECU, and no smog tech would know the difference between an EVO IIX-X BOV vs. the crap stock 3S valve...

You can easily double the horsepower on one of these cars without any danger of detection if done carefully.
 

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Discussion Starter #4
It worked! Well, not exactly. It didn't boost up past 14 psi. In fact it may not even get to 12 psi now...I have not gone much over 4500 rpm lately because it's been pretty hot, etc., so I'm not sure what the psi peak at 6000 rpm would be. But one thing it does do is ramp up to 7 psi very fast, much quicker than before. It can shoot up to 10 psi or a bit more but the high-rpm end is blunted a little. And that's OK, the mid-range torque spools up FAST now, really fast. I only left the clamp on the rear wastegate. The front one has a much thicker, stronger hose and it's in a weird area between a lot of large intake/coolant hoses so it's hard to clamp it. But there for sure is a difference in spool up time, even with only one wastegate clamped. It's a bit analogous to having a boost controller where the LO boost is set high and the HI boost is set low, and is rpm-dependent instead of low or high gear dependent. And that's fine with me. If I wanted top-end HP, I would have bought an E46 M3 instead.

Speaking of high-end horsepower, some auto writers are predicting a used-car pricing crash this fall, due to the viral quarantine disrupting normal sales. They think many used car prices will drop as much as 50% from what they were worth at the beginning of 2020. Could you imagine getting a 2000-2006 M3 for $6000 (they are 12K now). Or an 2008-2012 M3 for $12,000 (20-30K now). Redlines on those naturally-aspirated ones are 8000 and 8400 rpm. I have not test-driven the later E90-92 model, but the E46 M3 is quite a symphony, that direct injection double vanos really sounds exotic. Handles great, acceleration is a bit too smooth for my taste but still a great 2nd car. I'll try to get one for my wife and then I'll end up driving it for her lol.
 

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Stock turbos will fall off after 5k rpm. Not much you can do about that. Going catless would help, but it sounds like you dont want to go down that route. You could probably still get away with gutting precats and keeping a good main cat. But up to you.

I would not recommend only clamping one of the turbos WG hoses. You can access the front one in the area you mentioned, or on the other side of the hardline near the firewall. Just look at the stock vacuum hose routing diagram, should be online at stealth316 or under your hood.

If you are considering a used E90-92 M3, make sure you are fully aware of their issues with spinning bearings.
 

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Discussion Starter #6
I bought real f-clamps from Amazon this week. They said 4-inch, so I thought that meant 4 inches long total. Those candy cane handles are almost a foot long! And they weigh over 1/2 lb each, so I thought they may be too big and heavy to fit, but they did actually fit. If they slide around too much I may have to clean the engine around them and duct-tape them to the engine bay. Was able to clamp both hoses. Short test drive up and down my street, 15 MPH limit, so obviously could not open it up in 4th gear or anything. Boosted up to 14 psi in 2nd gear at a bit less than 4000 RPM --- it worked! I'm sure it can boost more than that in higher gears. Now let's see if the heavy clamps fall off or flop all over the place if I take corners too hard. But for now, yes, you can clamp the wastegate hoses as a cheap fix to get around the CARB rules. Every 1-3 years just take them off the day you smog. This does really seem to be a decent HP mod, ghetto or not. After all, it's not so much different than an EGR / vacuum hose delete, is it? I'll watch the boost and make sure I don't peg it too much, but the car more or less came like this when I bought it at the dealership with stock turbos (I think either the original owner or a mechanic disconnected the wastegate hoses before I bought it). So I don't think it's a huge thing to worry about, we'll see later either way of course.
 

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Glad it worked for you. But that's nothing to do with EGR/vacuum reduction. Doing EGR/EVAP/charcol delete and vacc reduction has zero effect on WOT performance unless you install a boost control at the same time and change the boost from stock. Doing the vacc reduction in itself doesnt increase boost, you would have to retain stock boost control, or, with no boost controller, run WG pressure.
 

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Go to home depot and get a small water valve. Usally the o rings inside get hot, and melt after awhile... so hook it up.. spend about a month getting your boost exactly where you want it, and it will eventually lock it into place. And, it will cost you around 10 bucks. Or even, go to petsmart and get one from the aquarium section.
 
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