With a
17% pulley
Milltek exhaust
Alta intake
it seems to me ECU stuff is the next step.
What are some of the best choices out there and why does nobody seem to use the Dinan tunes? I've only done a small amount of research but I haven't seen anybody talk about them.

 

Your next step should be BIGGER fuel injectors!

If you are going to get a tune, I would highly suggest injectors first, if you get the 380cc units you will not need the tune RIGHT AWAY, but if you go any bigger it will require an intimidate tune.

 

Dinian left the mini market pretty early....
Their canned "tune" did require that the fuel pump regulator be changed to a higher psi unit....
And have their kit installed....so you don't have their kit, still have the stock fuel system, and while Dinian still "sells" the install....they have been a way from mini's for 10 years....so pretty much a dead end...and not the best for so many reasons.....
Right now you are likely about 175 ish to the wheels......with similar I got about 185 with jcw380 injectors, then got a custom dyno tune get 200 to the wheels....a "canned" tune, no dyno will likely still get a nice bump...but less than a custom....
Running 380's with a 17% pulley is ok...not ideal, but mostly works (much better than a 15%)...but longer term, I suggest a tune....anything bigger than 380's REQUIRE a tune...usually same day (some folks do the install in the parking lot at the dyno)....

 

ZippyNH is totally accurate. As far as popular tuners there are many but some of them who are spoken of frequently are RMW, MYNES, WMW you have lots of research left to do as far as what just those 3 I mentioned can offer.

 

If I was at your point in my mods and I was looking for what next to do, I would do the following:

Save up a bit (as I dont know your financial point, but mine takes a little saving for these mods). I would contact RMW and order a DimSport Programmer and the 450cc Injector kit. I would let Jan know that what Mods you have on the car.

From that information he will have you, download the Firmware/Flash from your DME/ECU, he will send you back one that will be VERY close to a custom tune, for your setup. I dont know what he charges for the 'canned' tunes, so I can not comment on that, but I do know they are very good.

This is all assuming that you are not going to have a tuning party in your area, if you are in the future then you can skip the whole Dimsport box, and just get a custom tune done.