Car is jerking and bucking at mid to high rpms

Ok here is my new problem, Me and a friend of mine were going down the highway tonight when out of nowhere a red 240sx comes flying by me (ricer flyby) well he was doing well over a 100 mph so my friend was like NO WAY! , So I put the car in third gear and started to go after his big ego ass. Well as soon as I hit the throttle not even getting close to topping out third my car like bucked or jerked, I mean it literally jerked it felt like as if my car hit a wall or something it was a pretty strong jerk I could've lost control of the car, but I didn't I thought I blew the engine at first but I didn't so I continue chasing after the 240, again 4th gear my car jerks really hard. Finally I catch up to this cock moocher and we are neck to neck I look over and gave him a piece of my mind about him doing a ricer flyby on me so I gave him the finger. After that I put the car into 4th gear doing atleast abill 10 or so and started to signal him to race me now, he wouldn't give in at first but I let him have a small advantage on me then he punches it, so did I. I passed him as if he was sitting still, my car jerks again I put it in 5th and I start slowing down cause my turn off is coming up. I was hoping that the guy in the 240 would follow me so I can try to get him to race me from a stand still but he fly past me while I was getting off of the highway. So after that my friend and I start talking and we're tring to guess why my car was bucking like it was, I stated that it might be fuel cut, I have never had fuel cut before so I don't know what it feels like nor have I had spark blowout. My car other than that is running fine smooth as ever, don't really have much mods on her.
My Mods are as followed:
HKS Air Intake
Striaght pipe with both pre-cats still on exhaust
Free boost Mod ( removed the nipple out of the waste gate solidnoid)
New Turbos ( Custom built don't know what size they are 9b's 13g's , The turbos came from A1 Turbos out of California )

Thats it. I had a problem earlier with my y-pipe gadskit getting in my throttle body and getting stuck making my throttle body to stick at WOT, Now the gadskit is sitting in my passenger seat in the car, the gadskit was to big for the y-pipe so mitsubishi cut the gadskit to make it fit in the y-pipe thats what caused the throttle body to stick. So now I'm running with a y-pipe with no gadskit on it. The y-pipe is as tight as I can get it, and I get alot more air with out the gadskit in the pipe, my turbos spool up sounds loud as hell and my stock bov is loud as hell. So this brings up another question, To what harm will running my car with out a y-pipe gadskit do? Is this going to hurt my car REALLY bad in other words?

Well for one, when your driving at high speeds and your can jerks for the first time.. Dont keep going faster and faster.. no offence or anything but that wasnt the smartest thing. You may have a loose connection to your battery or so. Just check to make sure everythings good to go.

Ok so it happend at high RPMs right where getting ready to shift? I dont have ne hand on expernce with 3S's but if u havn't regapped u plugs it could be blowing them out. But i don't think it would cuase the car to "jerk" maybe a kinda sputter like wait wiat GO. So was it a jerk like that or like the sterring wheel jerked or the car moved side to side?
Also maybe somthing in the tranny?

The bucking is compared to as if you slammed into someone or slamming on your brakes, at high speeds.

Sounds like plug blow out.

deff sounds like spark blow out, gap the plugs down a little and see if it goes away.

You're running custom turbos that you don't know what size they are...and you have absolutely no fuel modifications or any kind of monitoring system like datalogging or wideband...no offense, but that isn't the brightest thing to do. You are racing your car and have absolutely no idea how lean you could be running...it very well could have been fuel cut. Fuel cut is violent...plug blowout is more of an on-and-off again hestitation.

Running the y-pipe without a gasket is probably causing a significant boost leak, which is costing you power and isn't great for the engine either.