The front and rear motors are both 1Kw. The front motor has less weight over it, and can be more likely to "peel out" under heavy acceleration. This may lead some people to think it is more powerful, but it is not. It is an issue of less weight on the front wheel, which is why on soft surfaces it can spin under heavy throttle. Both motors are equally powerful. If you lean forward over the handlebars, you will see the front wheel-spin is dramatically reduced.
One other factor is that a motor "power rating" (such as 1Kw) is how much Power can be applied to the motor without it becoming too hot (or damaged). If you put a 5kw motor on your bike, it will likely not become any faster. What would make it faster would either be a higher battery voltage, OR, having the motor controller unit (Controller) feed more power to your existing motors. On a stock Zeegr bike, 2Kw (total power both wheels combined) equates to 40 amps of current being pulled from your single battery). This is near the upper limit that battery can safely provide.
Your bike currently has a 48V battery. Generally speaking, getting 32 to 36 MPH out of a "geared hub motor" bike with a 48V battery is considered doing pretty good.
What your bike has in spades, is Torque. With both motors at full throttle, you are producing almost 170 Newton Meters (about 120 foot pounds) of torque. This is much higher than most eBikes. This torque figure is higher than most of the well-known speed bikes (such as the Wired Freedom, eCells, Motor Goat v3). This allows the bike to accelerate more quickly to 30ish MPH than most eBikes. But, there is more to top speed, than simply torque. Torque simply gives you more "grunt" when accelerating. With your high torque, the eBike can run through dry sand or mud at a higher speed than lower torque bikes, you can climb hills with greater ease.
I wrote a small article about changing out the shock. And yes, I started at 750 pounds, but then went to a lighter 650 pounds. I am a bit over 200 pounds. I also suggested a 550 pound spring for riders who were even lighter. What you are shooting for is about 20 percent compression of the spring when you sit on the bike while stationary. The spring stiffness value is NOT 1 to 1 with the weight of the rider and bike. It has a cantilever mechanism which applies pressure to the rear shock. This cantilever mechanism has a "mechanical leverage" to the force applied to the spring. This is why my bike (with a 200ish pound rider) works best with a 650 pound spring. You don't want too soft of a spring, which can "bottom out" when going over a bump. When a spring bottoms out, it can have a "hammer effect" on the pivot joints in the rear suspension. After enough "hammerings" it can cause damage at the pivot joints of the cantilever mechanism.
If you are willing to have a bit less torque, but want more speed, my suggestion is one of the "speed bikes" I mentioned earlier. All three of those bikes will take you to about 40 MPH (The Motor Goat v3 will hit about 45 MPH with a rider of your weight). I have a Goat on order, because (like you) I like the ability to have more speed. However, I know it will have less torque (110 Newton-Meter "Nm" of torque on the Goat).
This answer is fairly authoritative, as I own the same bike as you, and have worked as an engineer for over 4 decades. The key differences between our two bikes are some minor version changes, where your controllers are set a bit hotter than mine.