I shimmed my wastegate but questions
 

I shimmed my wastegate a few days ago with 2 washers and the stock boost gauge read like 7.9 psi. Now I shimmed it again and i added another 2 washers so it has 4 washers on each bolt. My boost gauge still reads 7.9, but I did feel a very noticiable difference when i added the other two washers. So is my shiity stock boost gauge suppose to be at 7.9? Or maybe i have a big boost leak. Any suggestions.

Found a boost leak, now it goes to 8psi. Im going to look for more.

so your going by the boost guage in the dash correct? if so it tops out at 8 psi and will just pin to the top after that. you need an aftermarket boost guage so you know exactly how much boost your putting out, espicially if you've already raised the fuel cut with the lexus afm and 550 injectors cuz you don't want to harm your engine.

i shimmed mine and i run 10 psi with the pedal 3/4 of the way down and 14 psi hitting fuel cut when its matted. the washers i used were a little thicker than i wanted but it does the job

Yeah I definetly need an aftermarket boost gauge, I was thinking about getting one at autozone the brand is Auto Meter, is this a good brand?

And also can two boost gauge's be working at the same time? like the stock and the aftermarket one?

i'm not sure to me they all do the same thing and there is no need to pay for a brand name on something like this. but also yes my stock guage and aftermarket boost guage both work. mine are something like mookee or something they were from ebay but work fine.

i have heard a lot of problems with autometer i have an autometer and the thing worked fine up until last week but if i move the wires going into it i can get it to work again, if its cheap enough they last a while til you can get better ones