Most of the good aftermarket turbos I've seen have been Garrett, which is a really good name in the business. If you are interested in turbos, check this PDF out:
https://www.turbobygarrett.com/turbobygarrett/sites/default/files/catalog/Garrett_Catalog_V5.pdf
Look at page 29, for your turbo. Then look next couple pages for bigger sized turbos. I like the 2560 models, essentially they are the same price as the smaller 2554. The slightly bigger turbo gives you realistically (in my option) probably another 25 HP between 5k and 7k. Some people have said 30-40hp but I'm a bit more conservative.
From all the research I've done, a GT2560R is the biggest turbo you can put on a 1.6L engine without getting noticeable turbo lag. It is a lot better in a straight line, but you lose a bit more torque under 3.5k. The 2560s are also the largest turbo you can fit with the stock fuel system. Anything bigger and you will have to upgrade that. For around 1700-1900 I think these are a crazy deal in performance. However, you will have to take a look at intercooler threads. An aftermarket intercooler designed for the stock turbo may or may not be up to the task, depending on the design. This really matters if you take your car to the track. For 1/4 mile drag runs it doesn't really matter since your are only running your engine hard 14 (or less
![[twothumb]](/images/smilies/icon_smile_twothumbs.gif "Two Thumbs [twothumb]")
) seconds at a time. On the street, the larger turbo won't doesn't spool up until 3.5-4.5k rpm. In these conditions you can actually run slightly cooler with better gas mileage versus the stock unit since you aren't always in boost. Check out the air flow plots for your turbo and others on that PDF and see what works for your needs. Those plots are a little funky to read, but if you look at them for a few minutes side to side you can start to see the differences in their behavior.
Have fun!
