Chiptune or map with M16A swap

Thanks for reading 

I'm going to do a M16A non VVT swap soon having got my hands on an engine and I've done a wee bit of reading on the subject

I understand (some do, some don't) the deal with it potentially being iffy on emissions when using the M13A ECU

Can anyone expand on this and narrow it down to something more specific why the tune is a little out? 

Is it less air creating a slightly richer running with the bigger 1.6 injectors and smaller 1.3 TB/Intake manifold or timing or too hard to say, and it's abit of everything being out?

Is there any scope to improve it just a little bit more without swapping to a full standalone ECU. Maybe something like finding an M16A throttle body for example or using a chip tune plug in or even mapping the existing M13A ECU (anyone know of anywhere that can do that?)

My aim isn't big power by any means, just to improve things in favour of better running and make a decent job of the swap

Many thanks! 

Where have you read about emissions problems? In my experience the standard ECU quickly learns and adapts to the 1.6 and the are no further issues. I've never heard of anyone having problems with emissions after the swap.

Emmissions Havent been an issue for me even though my two cats have been replaced by one.
I am sure there are 5 or so more hp to be gained by doing lots more to it.
My donor liana VVT engine had the same throttle body as my m13 so I never swapped it.
My donor engine got way higher compression ratio than the original engine. So from that a bit of pre detonation ignition ping at high revs is my only issue.

Other than that it runs Great. I do have the impression it is as fast and uphill a bit faster than a gen4. Even with my trailer it can keep up with traffic. Even done a few overtakes Today coming home from Denmark, 1000km

I got a liana throttle body from Poland 
Couldn't find one in the UK 
They're a little larger bore diameter and makes a big difference imo

www.bigjimny.com/forum/6-jimny-chat/61909-throttle-bodies
there was also that thread.
My 2007 Liana was the same as my 2005 jimny TB.

Some say it is the earlier non-VVT liana that has the 50mm throttle body, up to 2004 -ish.

I also bought an intake manifold (aluminium) from a GV m16 to see, but it was just the same one as my Jimny m13 manifold.

With a larger TB the speed of the air will be slower so there is no need to go insanely big and mess up the venturi effect.
The 50mm one seems to be a good choice.

From Wikipedia:
1.6 M16A MPFI VVT (SX4 Hatchback 2WD/4WD - Europe)
Compression Ratio 11.0:1
120 PS (88 kW) at 6000 rpm
156 N⋅m (115 lb⋅ft) at 4400 rpm

1.6 M16A MPFI VVT (SX4 S-Cross 2wd or 4wd)
Compression Ratio 11.0:1
Maximum output: 100 kW (136 PS) at 6000 rpm
Maximum torque: 156 N⋅m (115 lb⋅ft) at 4400 rpm

1.6 M16A MPFI VVT (Swift Sport 2005-2011)
Compression Ratio 11.1:1
125 PS (92 kW) at 6800 rpm, 148 N⋅m (109 lb⋅ft) at 4800 rpm

1.6 M16A MPFI VVT (Swift Sport 2011 - 2014)
Compression Ratio 11.1:1
100 kW (136 PS) at 6900 rpm, 160 N⋅m (118 lb⋅ft) at 4400 rpm
Redline: 7200 rpm

1.6 M16A (fourth generation Vitara 2015+)
Compression ratio 11.0:1
Max power: 120 PS (88 kW) at 6,000 rpm
Max torque: 156 N⋅m (115 lb⋅ft) at 4,400 rpm

I might consider looking into one of these engines some day. 
The extra hp must come from somewhere, and as we know suzuki, parts will blend between models.

A slight tangent: Yakuza - you mentioned a new cat which (partially) solved the pinging problems you'd been having, and have also mentioned it in a different post (The Jimny of the Yakuza, way back in 2017).  A quick question for you - do you remember which cat you ended up getting (e.g. sizes, flow rates, etc), and any modifications you needed to make?  Bit of a newbie here, my M16A conversion is doing the same thing.  Thanks!