Can anyone offer their professional opinion on what turbo setup is the best bang for the buck? Should I upgrade my T25 to a Garrett GT28RS for around $1200 or just pick up a used T28 ball bearing from a newer SR20DET for around $300? In other words is the Garrett worth the extra money?
well they are both garrett turbo’s. but first of all pick a horse power goal. then research on what you’ll need to do it. sure anyone can slap a bigger turbo on their car but will it spool at lower rpm instead of hitting full boost at 6500 or higher. i use to build nissans, honda,s etc. everyone wants big hp for cheap and horse power doesnt come cheap. gt28 will get you around 320whp. im hitting 250whp with my stock t25 at 15psi. and i think the rs will get you around 400whp. if the fuel is there. hp is all in the tune.
if you wanna talk turbo’s talk to got boost on here thats the guy i used to build cars with. he’ll point you in the right direction.
Also consider other hardware needed to run the T28. You may want to consider Taka turbo lines (i’ve never used them, everyone dick-licks the lines since they’re soooo easy), etc.
On top of that GT28RS if that’s what you want, you’re going to need at least 550cc injectors, a Z32 MAF, some sort of engine management, and a walbro fuel pump if you don’t have one yet.
If you don’t plan on changing all those things, there’s no point in upgrading to a gt28rs, cause you can max out all of those things on your stock T25.
^^^^ exactly
gt28rs doesnt start to spool till 3600-3800 rpm
t28 spools sooner so for street response go with a t28
gt28rs requires fuel up grades right away and you might want a bigger maf too
t28 does not require you to upgrade right away untill you start uping the boost past 15psi i believe(anyone please corect me if im mistaken)
so it realy depends what you want to do power wise and how much you want to spend right off the bat.
Mael
(i run a gt28rs)
Sorry dude but squeezing 320whp out of a T28 is next to impossible. Maybe 300whp if you have the S15 turbo and every supporting mod. I make 320whp-ish and I run a 2871R. The limit on an RS is 350hp so about 300-320whp is realistic. There is no way you’ll get 400whp out of an RS.
what i read up on KAT.org is that the GT28RS is almost, if not the same as the S15 dual bb turbo.
GTiR T28 from a Pulsar… biggest turbo nissan used on any factory engine and is bigger then the S14/S15 T28 BUT its not BB which means it’ll spool say 500rpm slower BUT it would cost a 3rd the money to rebuild…
I run one myself but @ 8.5psi I hit 98.7% injector duty on 370’s and the MAFS is @ 4.93V… so you dont exactly have to upgrade either right away unless you play on going past 9psi right away.
They also have the exact same hotside as a 2871 and can hit 300whp depending on mods… dude on 240sxforums.com makes right in around 320whp but has every supporting mod possible + runs it @ 22psi I believe.
Hey Jeff, is that the same turbo that Benson is running on his car as well? How fast do you build 8.5 psi in that turbo?
And no, the s15 turbo is way different than the gt28rs. The inlet is different (but you might be able to get it made like a stock t25/t28 inlet). The S15 turbo, like people have said, is good to about 300whp with supporting mods.
The GT28RS could hit around 320+ whp if you have the supporting mods as well.
It would definitely help if you had cams though. 256/256 or 256/264 would be good for either one of those turbos.
yea its the same turbo Benson has…
I see 8.5 around 3400rpm… turbo is fully spooled to 0spi or what not by 3000rpm so anytime after that the party starts 
Good chat, keep the responses coming. Right now, I’ve got the fuel pump, need the injectors, have the AEM EMS in the box still, I’ve been looking into cams, and still running stock boost.
I’ve got 210whp and dropped a 14.4 in the quarter mile with an open diff. I’d like to see 300+hp on the street and not be rolling around all the time on boost. I’ve been thinking about a larger turbo for the job and of course all the supporting mods will be put into place.
I’ll be needing a good tuning shop to set up the AEM so if you’ve got any ideas…
I know it’s your car and all and I don’t know how you’ve modded it but if you have not done suspension, you should get on that before anything else. Lowering springs don’t count.
If you have already done suspension and tires, then ignore that.
Also, with 300whp, I hope that your brakes are somewhat upgraded, at least 180sx brakes with HAWK HP+ pads, but even that is kinda weak for that kind of power.
If you pretty much just want 300+whp, i’d suggest doing this.
S15 Turbo (Try to get one brand new)
550cc Injectors (Nismo, Tomei, Sard, anything brand name)
Z32 MAF (Make sure you find one with the pigtail still intact)
Exedy Stage 2 / ACT Heavy duty clutch or w/e / or any clutch that will handle above 300tq.
Engine management (I guess you already have your EMS)
3 inch full catback exhaust
Cooling might be an issue so I’d suggest getting a FMIC
An upgraded radiator would help too, a KOYO is the best bang for your buck.
And when going with the S15 turbo, if you want to retain your hotpipe position and turbo inlet pipe the same, invest in a set of those S15 Turbo adapters. If you put those onto the s15 turbo, everything will line up just like stock. 
By the way, if you’re just running stock boost, why dont you just turn it up to 10 - 12 psi, it’d be a lot more fun that way.
Good luck.