can someone explain this a little more...you just unbolt that hting and slide it down and re bolt it and it increases what???? and where is thi son my 92 ssei?

It had no noticeable effect at all for me.

Maybe it only works if your boost control diaphram is old and slow or if you're trying to save .001 sec in your 1/4 mi time.

Go ahead and try it anyhow. Nothing to lose.
it is the black diaphram with a small linkage that sits just above your water temp thermostat.

Exactly. People on club gp always complain about having to buy premium gas, or that they don't get good gas mileage, and then 2 minutes later they ask how to get 30 more horsepower. You can't really get both. My dad and I just shake our heads. It is crazy. My dads car is making 400hp, and he will gladly go to the gas station and fill up with 94 octane gas every time he needs it and not complain about it, because he drives a fairly quick car. If you want good gas mileage, buy a Metro, if you want performance, don't complain about gas mileage. I do have to say though, that my dads car actually gets better gas mileage now than it did stock on the highway, I would think because the engine doesn't have to work as hard, but I am not sure. He gets about 30mpg on the highway, stock he got 28ish. His city gas mileage went down because he drives harder with the extra power, and he has higher shift points and such. But, 30mpg is not bad for how fast the car is.

You just contradicted yourself.
400 hp and 30 mpg is having both power and economy (when you want it)

My complaint was around my slightly more hp than stock and 15 mpg !

....but I think I've figured out why. Not enough steady highway miles over the course of a full tank. To much stop and full throttle go.
Even so, I'm hardly getting better mileage than the 400 cu in 4 barrel guzzler Firebird on the same roads....and it has a bit more giddy-up, though not as much as your Dad'* GTP.

I use 94 Octane plus and Octane booster in all my vehicles.

Sorry I'm so I'm ending it now.

I started on the mileage thing relating it to the topic to find out if adjusting the boost bypass would reduce the mileage whether or not one is heavy on the throttle.
I know now that it doesn't make any difference.

Yes, I know. I was saying that it was weird, but in the city it obviously gets worse. I do not know what the problem is with your car though. 15mpg is bad. My moms DIC (the SSEi) has never been reset before, and it says 20.3mpg and that is for ~73,000 miles. It probably is just your driving style like you say, but that is still odd, it shouldn't be that bad, we drive the SSEi plenty hard, and it doesn't get that bad of gas mileage, but i guess it has a lot of highway miles too.

And no, as you already figured out, the Boost Bypass Valve mod will not help or hurt your gas mileage, or at least not a noticable amount.

94 Octane and Octane booster! What do you need that for? You can put whatever you want in your own car, but that seems kind of unnecessary to me, it seems like just regular 94 octane would be just fine.

Does this mod only work for the L67'* only? I have the 92-93 supercharger. Is this the L27? What can I do to get the mod done for my car?

L67 is the RPO designation for all factory equipped Supercharged 3800'*. In other words, although there are differences between the '92-93 Series I, the 94-95 Series I, the 96-2000 Series II, and the 2001-2004 Series II, if it has the supercharger, it is still an L67.

But to answer your question, I have not yet gone out to see if this will work with a Series I L67. I will check after work. I suspect that as long as we have the same setup for the bypass valve, it will work.

I didn't know there was so many variables of L67.. what'* the benefits and rating of each? For instance.. I only thought there was series I from 95 down ( to certain years that I can't remember ) 225hp and all 96+ series II L67 were the same.240 hp ( minus the GXP @ 250hp )

Any info would be apprecited.. spanx

1992-1993 L67 had 205 hp
1994-1995 L67 had 225 hp
1996-2000? L67 had 240 hp
2001?-2004 L67 still had 240 hp, but had some differences--not sure to what extent. I also heard through Intense that the series II L67 heads improved in 1998 over the 1996-1997. Something to do with cracking around the exhaust valves (not the valves themselves, just the valve seats) if you did a ratical valve job on them. For people running stock, there should be no problems.

As for the actual break in the series II, I am not sure if it is 2000/2001 or 2001/2002, but I caught just a snipit of information regarding a difference in the */C, the trottle body, or the fuel rail, something to do with the air/fuel system. You should check with someone who has intimate knowledge of the third gen Bonnevilles.

Since I don't have an Auto Tap scan tool, I thought it might help the Knock Retard issue.

I have to use it in the Firebird, and it makes a noticeable improvement.

I don't think it can hurt.....only an extra $4 a tank full.