EXUP removal disadvantage????

I've been doing a bit of research on aftermarket exhausts available locally in Oz and have been told by a very well respected Aussie exhaust specialist that by adding an after market exhaust sytem and removing the EXUP, I'll gain extra power top end but I'll be losing valuable low end much needed torque and with a 250 trail bike used for single track knarly hill climbs you need all the torque you can find.

Have you guys that have removed the EXUP and added different pipes noticed this low end loss of torque and felt disadvantaged??

I found a few old posts here on aftermarket systems that retained the EXUP such as Leo Vince systems but there hasnt been much of a follow up....

I've heard that, too. But IMO, the gain from an aftermarket pipe is across the board.. i felt i got both top end & low end power increase. ..not a lot, but some. definitely noticeable. I'm pretty skeptical of power claims, especially seat of the pants measurements. I can't say i noticed much from the airbox mod, ais, even a programmer. But with the pipe i did. I'm a slow modder.. i do one at a time, with riding time between mods (mostly a financial thing). IMO, the pipe is the main thing you can do to pep it up a bit.. combined with opening the airbox, of course.

As usual, the advice you get here is worth what you pay for it..

You'll be way ahead by replacing the stock, plugged-up muffler with an aftermarket one without an EXUP valve on it.

If you do that ALONG WITH getting rid of the airbox inlet flapper, adding a fuel injection programmer, and gearing the bike down for single track gnarly hill climbs, you'll have more power everywhere and much better throttle response and won't think about the EXUP again.

I believe there probably IS some power loss if you just remove the EXUP valve. Yamaha puts it there to give the bike some much-needed bottom-end with the stock setup. However, once you uncork everything, the whole bike comes to life. Perhaps WITH and EXUP valve you'd have slightly more bottom end, but from my butt-dyno, without it the bike is just fine.

I took mine off put on a FMF PC4 and a PC5 and geared mine 12/48 and my bike never starts in first gear If I go up a rocky hill in first I fight to keep the wheel down on the ground it's sometimes hard to keep it down in 2nd..
My friend is a better rider and has a KTM 450. I keep up with him and can go up or down anything he can. He is a bit faster in the turns but that cuz he has way more dirt time then me and I'm not that far off. Rip that F-er off and put on a nice pipe and a PC5 and enjoy a new bike.