gained 8kw when you went back to standard ecu? Lol ok

Ill do a dyno run standard ecu v blitz. That way i have a dyno graph to prove my case. But at the end of the day as long as im happy who cares.

I'm going to call BS on the 'custom' tune, based on the following observations.  Most of the PnP ECUs available from the likes of Blitz, Sard, HKS etc. were just tuned ROMS with more aggressive IGN timing and slightly better fuel maps, no speed/fuel cuts and a higher RPM limiter (around 8000rpm IIRC) and were intended for use on stock (or mostly stock) engines.  The common factor between them all was the requirement of premium grade fuel (like the 102? Octane available from the Japanese pumps).
Back in the early 90's, custom tunes for the end-user would have been left to the likes of the Piggy-back Fuel computers like the HKS FC and suchlike.
 
 Many people ran into issues with them when they changed things like the turbocharger, boost pressure, timing (distributor), fuel system or electrics.  I've seen several cars with PnP ECUs from the 90s start detonating and reverting them to standard issue ECUs fixed all the problems. 

EssDub
I'm going to call BS on the 'custom' tune, based on the following observations.  Most of the PnP ECUs available from the likes of Blitz, Sard, HKS etc. were just tuned ROMS with more aggressive IGN timing and slightly better fuel maps, no speed/fuel cuts and a higher RPM limiter (around 8000rpm IIRC) and were intended for use on stock (or mostly stock) engines.  The common factor between them all was the requirement of premium grade fuel (like the 102? Octane available from the Japanese pumps).
Back in the early 90's, custom tunes for the end-user would have been left to the likes of the Piggy-back Fuel computers like the HKS FC and suchlike.

Many people ran into issues with them when they changed things like the turbocharger, boost pressure, timing (distributor), fuel system or electrics.  I've seen several cars with PnP ECUs from the 90s start detonating and reverting them to standard issue ECUs fixed all the problems. 

I did a lot of research when I was looking at getting one and I did hear about this 'custom tune' thing, but no one actually knew where this info came from. Yes they were intended for use with basic 'bolt ons' only, like exhaust and air filter etc and premium Jap fuel (not the swill in Aus). Hence, I wasn't going to blow $500 to find out.
Hope "adisco" does this back to back test on a dyno with the stock ECU to reveal whats really going on, rather than just anecdotes. 

The mid-range improvement would have been from the engine not drowning in fuel, lol. 

I didn't put it on the dyno though it definitely gave the car more grunt.

Old thread, but thought I'd toss in a few thoughts.
The Blitz Access did come in a custom tune option, but from all reports back then, it was very scarce, and marked accordingly on the ECU. The stock version dyno'd out to a 45 PS power increase on 100RON; I do have the dyno specs somewhere if anyone is interested.
The main changes were, apart from the fuel/speed cut, 17 psi boost and RPM limit,  confined to a re-mapping of the ign advancve curve, and surprisingly enough, a very limited amount of change to the EFI. This was confined to the very upper range of the high boost map, and although extensive in magnitude, limited in range.
Still have both maps I think, but in a previous computer.
You need to run 100RON or an ethanol mix to get the most out of it. On 98 you'd be better to drop static advance back a couple of degrees to keep the advance curve useable.