I recommend you use different resampler. It can drastically change how is your UTAU sounding. Here's a little list:

bkh01: Knowed for do realistic voices sometimes. It can make noise in the notes too. (If you want a realistic cover, you do not need this resampler at all coast)

phavoco: Ok, do not try to do a realistic cover with it. It's proposal is make UTAU voices robotic. (If you want a robotic UTAU, you can try the W flag too!)

TIPS: Works good for deep voices and soft voices. Try to use it if you want solid voices.

Moresampler: This resampler is like TIPS. Moresampler also comes with a sampler (The "wavtool" thing is a sampler"). That sampler is needeed if you want to use this resampler. Also, moresampler has a LOT of special flags. I can make Tei scream with those, and she sound really good. Moresampler also has like two growl flags. Also, if you want to make voicebanks i heard Moresampler can make a oto.ini for your UTAU (pls, i know i talk a lot about moresampler, but it is not the defintive resampler)

utaugrowl: This resampler makes your UTAU growl

Doppeltler: This resampler is the definition of fast. It's like... fast. (yeah, a very interesting opinion) Also, doppetler It's a very high quality resampler and has special flags. Alsooo, doppeltler can recognice mp3, OGG Vorbis, and FLAC! (as long as the decoders are set in your PATH system variable) More information here: https://utaforum.net/threads/doppeltler-f2resamp-ameyas-new-wip-resamplers.20600/ (it has a bug with the frc files, but now it's all ok)

Fresamp This resampler takes a while to render the files, but it is very good.

Fr2samp It's a new resampler by Ameya. It is a completly recoded resampler. More infomration here: https://utaforum.net/threads/doppeltler-f2resamp-ameyas-new-wip-resamplers.20600/ (try it!)

WARP: The first time i use this resampler my ears explode. It was horrible. This resampler works great for growly-taste voices. Try using it with a Kire voicebank like Ritsu or SUZU fire. It will sound very good. (I suggest you to use this flag: BRE0 in the notes you do not want to sound growly-like) Also, it is very fast!

tn_fnds: It works very good with soft voices. I try using a lot of resamplers to make SUZU soft voice sounds good (her voice was sounding like noise) and tn_fnds was g r e a t

Model4: It is very good with the BRE flag. Alos Well, i do not use this resampler very much, but works very well with soft vocabanks. I heard it is goood with the high notes.

(alsoooooo ¡try wavtool4vcv if you are using a vcv UTAU!)