there would be a couple of things i would be looking at .
You say more competitive , how close are you to the top cars in your class ?
Next look at what they run , scrute bay at an event is the place to be , look make notes ,and if your not comfortable get someone else to do so (do it before the close of season)
Setup will be key especially for a sprint car , as is weight , what can you loose within regs (losing weight is almost always free!!)
After looking at what others at the front are using make a judgement on suspension setup , but ask yourself what does the car not do that I want it to ? A new set of suspenders isn't always the magic answer.
Lsd on any competition car is a worthy addition (almost a must have ) don't waste what power you have .
Is it stopping as well as you want,need , a winter brake overhaul and maybe a change of pad material can help .you'll usually make up more time stopping than going .
Driver training (notice i haven't mentioned more power yet) get out on some track day , and hire a driver coach , you'll be amazed at the time you can gain from this , and do it a few times a year and it can and should give you the edge , remember anyone can bolt the right bits on a car , extracting that from it isn't half as easy , this can also help you work out where you need to go next with the upgrades as it will start with a good coach to help you identify what areas need improvement .
Get your arse in the gym , get fitter, alerter , and have an edge over your fellow competitors ........
most of that might sound like its pulled straight from a book , but its actually down to experience over the years on getting to the front , its a cost effective route as well , and THEN you can look at more power ,however doing it this way should keep the engine reliable as extracting more power always starts to lower the overall reliability factor.
Hope that gives a slightly different route to being competitive , far to many people go straight for the big power ,but you can bet anything thats not why the guy at the front is where he is .