This is a review of the MaXspeedingRods Rb25 Bolt on turbo.
The Specs for this turbo are on there website and here is the link: https://www.maxpeedingrods.com/product/nissan-skyline-r32-r33-r34-rb25-rb20-max-21.75psi-turbo-turbocharger.html
As per any aftermarket turbo, it has its limits and it should be setup in a way that its following the manufacturer rating to get its maximum efficiency and power gains. Do not expect to push it to ridiculous psi and to its absolute limit as it probably wont end well. That goes for any Brand name turbos. These turbos are rated for 16-18 Psi. A youtube channel Leprechaun Laboratory tested these turbos with their dyno and looking at the results it starts falling of its efficiency at about 18 psi which is surprisingly good. This turbo is a little bit bigger compare to the stock turbos so from my experience it its a few hundred rpms laggier compare to stock but it is able to boost higher and harder compare to the stock turbo. Im running 15 Psi on my setup at the moment and it performs really well and the spools sound is definitely better compare to stock.
I think these turbos are great specially for the price. You get rid of the ceramic turbine blades on the stock turbo which means can boost higher with these turbos. The overall quality is surprisingly really good. bot compressor and exhaust side are balanced and every nuts and bolts have markings on it which states that its checked and tighten to specs. I know that these turbos might get a bit of hate as its a budget turbo but comparing it to the stock rb25, rb20 or neo turbos on the market and their price, these turbos are perfectly good and great for bolt ons.
Now for the negative. These turbos came with a really small wastegate hole as shown on the photo. YOU HAVE TO port the wastegate hole to avoid boostcreep! once ported works perfectly fine and performs well. If you are still running the stock hard lines for the oil and coolant lines, you have to slight work around and slightly bend the lines when installing it to the turbos. If you already have braided lines then that shouldn't be a problem.
Other than that these turbos are great as a bolt on replacement turbo as long as you treat it well and do not max it out to its limits.