This particular Ultimate benefits a lot from light weight,
I have seen it flying with:
OS 120 4-s.
YS 90 4-s
and OS 90 FX 2-s

I flew it for a little over 3 years with an OS FX90 2-s and a APC 15x6 perry pump , other friend flew it on same engine but 13x6,
( I fly at sea level )

this plane just dive when throttle comes to idle, funny way to approuch I will say, and if not landing with speed you will find fixing your landing gear often, as a matter of fact, reinforcing it now makes sence !

I think a SAITO 125 is flat out too much and adding a smoke system on top of it you make run the risk of not enjoying it as much as possible for overweight reasons !!

I used to do all type of nice aerobatics and my combo will sustain nice knife edge, knife edge "L" ( sort of a knife edge loop ), full throttle take off to imelman to name a few.

It went to major maintanace and now a days sits in my hangar orange and white ( gone is blue & yellow ) and ready to fly but has not seen action in 2 years, a pitts monters and a Balsa USA Dr.1 + my magic are
eating up my Saturdays.

Try your best to keep it light, if SAITO 125 is already purchased, so be it but, do not place a smoke system as yet; fly it first and get a feel of it's landing speed before adding more weight to it.