[vagthomas]

Very interesting findings after tuning (ProECU from ECUTEK) my GT86 and
a friend's of mine at the same day at the same dyno.

List of Mods
============

Mine: K&N Filter and TRD High Response Exhaust Muffler. Rest stock

Friend's: K&N Filter, HKS Resonated - Decat Front Pipe and Legamax Axleback. Rest Stock.

Tuning
======

Mine: Dyno test prior tuning showed 166 whp. After tuning we were at 173
whp and an increase of torque on an average of 0.7-0.8 kg within all RPM
range. Tuning not finished yet. With some further changes we expect to
gain 2-3 whp more.

Friend's: Dyno test prior tuning showed 155 whp (only)!! AFR was lean
within all RPM range (3% from target low, 14% from target mid, 23% from
target high). After MAF Rescaling, Fuel Trim optimisation (both closed and
opened loop), AFR Remapping, avanche, various other details that only my
tuner knows and without Touching VVT (yet..), the car went 169 whp and
gained 1.3 kg torque within all RPM band!! Basically, this is another car!!
That was correction of the system and not tuning!! Tuning though is not
finished yet. Expecting to get 5 whp more with some further changes as
my tuner advised.

Imortant detail: Both cars never tuned in the past. This was the first time!!

CONCLUSIONS
===========

This car's air and exhaust system is fully optimised from factory. The
replacement of front pipe with resonated de-cat HKS and axleback
Legamax most probably increased the vacuum in the cylinders (exhausts
flowing freely), therefore more air coming inside..air that could not be
handled by the stock tuning, leading to lean AFRs. The percentage
differences from target noticed high are so big (23% !! ) that someone
could even say is dangerous, in case you drive the car always on the
limit!