Getting my "used" front bumper back together, and it came with a carbon fiber "splitter" that stiffens up the bottom of bumper nicely.
I'm not running any of the factory bumper stiffeners, except metal strips under headlights. I tried to put back stock undertray and due to
IC size (depth), it's the same thing as before (won't fit without completely hacking out center of it). I don't want to hack it up, as I'm going splitter
eventually in the front.

Don't want to spend time or money on a rear wing right now, but hate to make temp undertray that will just be replaced soon enough.
So will it be horrible to run a front splitter and stock rear wing? I guess I could try and make it so it sits a bit farther back for now, but
has enough material to be moved further forward, if/when.

Also, would a rear diffuser help any if I went with front splitter only (again, with stock wing). I also got a used rear bumper and can hack
that up any way I want. I have alum sheets I got for free, that I was planning on some sort of diffuser, so could build that almost no cost.
( I'm getting "adequate" on this new alum MIG/spool gun setup I got last year)

honestly i doubt ud notice much. in theory too much front downforce should induce understeer but unless ur a top level driver extracting everything out of the car already i doubt ud notice much

Should be just the opposite of that. Adding front splitter going to add front grip bias. Balancing with rear wing will add rear bias. Total grip increase isnt huge, but its not nothing.

Don't want to add any more understeer if I can help it. Other option is to find a used stock undertray and hack it up to fit.
Might be the way to go for now.

yea sorry theoretically it would add oversteer.

But unless its like WTAC cfd style aero i doubt youd notice much.

If that's true I would think about adding it now. Even with my limited track experience I can
see how bad these things understeer.

As everyone is saying, unless it's a crazy efficient splitter, you will not notice anything.

From factory, our cars are setup to understeer and people go though massive lengths to fix this. Adding a simple splitter will not do much.

" Not do much" is also fine with me. I just didn't want to put in a "basic" splitter now, if it was going to significantly, negatively, affect handling.

yea honestly i doubt ud notice much difference

it all depends on how big you're going to make the splitter and how low it sit. if you're just going to make something tiny like an APR splitter and sit at stock ride height, you wont notice much of a difference. same goes with rear diffuser, depends on how you design it. a rear bumper under cover is not a diffuser, it's just anti parachute. when i ran my car with splitter and rear diffuser, there was a slight over steer. without the diffuser, it was very oversteer, so the diffuser definitely had an effect.

https://www.evolutionm.net/forums/pr...l#post11408652

I personally ran an APR splitter with the stock wing for a while. I did notice improvements on front end at high speed turns on road courses and the straights as well. There wasn't any more front end getting light feeling that I noticed on the straights anymore. AX however I felt the understeer more in low speed turns but that could be in my head and s*itty driving lol. This was all at 320ish WHP

Get that stock understeer tuned out with suspension and alignment first. Add aero later.

The stock understeer is easy to tune out with standard suspension setup. We'll always be front-biased, but the car can still be adjusted toward neutral or oversteer.

I'm not sure how effective that APR piece is anyway since its not rigid mount and essentially just pulls down on the bumper. But I suppose it would clean up the air a bit under the front of the car.

I'm currently in a similar situation. A couple of years ago I got some custom Olin's with 10K rear springs with the intent of getting a big wing eventually. With front and rear at -5 clicks I definitely felt oversteer. Backed off the rear to -7 clicks and the car feels vary balanced. Hope to get the wing soon.