Rep Power: 0

So I've gotten my ex auto to lx manual swap done. I burned the trans out on the ex auto and decided to just transplant the lx manual. I was driving the car manual swapped with the automatic ecu since the antitheft matched the key maybe for the last 4 months like that with the car in limp mode(4k rpm rev limit) for the trans code and the vtec code.

I've finally gone around and gotten the key flashed for the manual ecu and now that I can drive the car past 4k it feels absolutely dog slow. I know my ex wasn't this slow nor was the car that this was taken from.

Is there something that may have happened from me driving around with the lx motor on the ex ecu? even though all the driving was obviously 4k rpm and under?

 
Rep Power: 223

You swapped engine and transmission? LX engine is non-vtec so of course it will feel slow. LX manual transmission has longer gear ratios than EX manual transmission as well.

 
Rep Power: 222

What ecu is currently in the car?
lx manual trans has longer gears like BrotatoChip said

 
Rep Power: 0

So, ECU is LX Manual, engine and trans are matching LX manual and car was an EX auto. I've driven them both, the ex auto and the LX manual before deciding to gut it and move it so I know its nothing fast by any means but I guess its hard to describe the loss of power.

I guess I'm just trying to find out if there was a problem that could've arose from driving causing me to be down on power the higher into rpm I get. I haven't really tried to bring it to redline since I first got the immobilizer flashed to the ecu but when I did, it was struggling to get up to full redline. It was as if it didn't have the power to get to the redline and almost sounded as if the fuel was cutting out like the car was sputtering near redline.

 
Rep Power: 223

Check for fault codes, check for exhaust restrictions, check for intake restrictions. If you think fuel was actually cutting out, check fuel pressure.

 
Rep Power: 222

Lx ecu wont activate vtec. Since it doesn't activate, the high rpm profile on the cam isn't used which would probably make the car run like you describe

 
Rep Power: 366

Using EX ECU with LX engine, aside from the VTEC and trans codes, should not damage an engine - it goes into limp mode to protect engine from damage.
Did you do maintenance on the engine before you dropped it in?

Compression good? Belt timing good? Sensors good? (If you change them, always use OEM sensors)

 
Rep Power: 0

Okay cool, primary worry dealt with.

No maintenance all throughout the process, oil change was done a month before the swap and the motor sat between cars for maybe a month with the trans still hooked up so no fluids or sensors changed. I'm unsure honestly of the compression and timing but I guess those are things worth checking?

 
Rep Power: 0

Will check for fault codes today, I've been putting it off with the ECU mismatch cuz trans and ecu codes.

intake restrictions on a little k&n typhoon intake? what could/should i check for filter dirty or like something inside?
same with exhaust what should I look for just like pinches or something? stock lx exhaust with no muffler lol

How could I check the fuel pressure at high rpm? It seems to happen 1st and 2nd gear, full throttle and higher than 6.3k roughly it starts to sputter or spit somewhat.
(I honestly haven't just revved in neutral to check but I should.)

I've had the fuel pump fail on the car before so I know how it feels when it sputters because of fuel pump but when it failed last time the issue would have the car almost seem lose power at 3.5k and it would sound like the car was just spitting fuel keeping itself on so this just seems different to me.

 
Rep Power: 366

Unbolt at the throttle body, then try driving around the neighborhood (they gonna complain about the noise )
Then unbolt the header at the head and do another drive around the neighborhood (they gonna complain again about the noise but absence of muffler already puts you in the ears of them anyway )