Mg Metro 1275 With Spi's Single Injection And Spi's Std Head 35mpg?, single injection match mg metro? how to improve? Options

[ROXTEE]

Hello Everyone, I posted this one on problems, qustions and technical, but
seems its more injection related, so I post it here to see what you guys here
will suggest.

I recently had an engine swap, below is the facts:
Standard MG metro Engine block 1275cc from standard mg metro.
Standard SPI's cylinder head (from standard 1275cc spi engine)
standard SPI's ECU (from standard 1275cc spi engine)
standard SPI's single injection unit (from standard 1275cc spi engine)
standard gearbox, 3.44 final ratio
K&N air filter
LCB RC40 EXH and twin DTM tail silencer
the injection system and ECU all come from the same car---my previous spi
1275cc, actually, the air filter and LCB RC40 whole exh system all from the
same car. only the enging block and gearbox is from MG METRO.

The fuel consumption is ~35 mpg and this is under very normal driving style:
no high rev, very gentle gear change, top speed no more than 70 and average
speed 90% of the time 50-60(4th gear). I think 35mpg is a bit too far for that,

I was been adviced that the fueling and timing all is controlled by ECU, so what
could be wrong what can be done to improve the problem? could anyone give me
some suggestions?

change cam will result in engine out and in, its not something i would like/ able
to afford to do at the moment. I just want to see what can be done to the existing
engine system, by some minor modification.

from what u guys suggested, the ECU can not be mapped/adjusted, how about change
to a cooper's ecu? will that make it better?

what im really concern it: my mg metro + spi injection probabily is about 70+ bhp now,
for this kind of power, not very much, so that makes 35mpg seems too much compared to
the power, that's why i want to do make it have a better mpg to match the a bit low power.
am i wrong on this?

I also would like to know what will happen if I change the cylinder head to
a stage 3 sort type of head?

Thank u very much for your help

Regards

Roxtee

[datsun100a]

You'll get the same answer here, "Cam Change"