Can better parts.....

Maybe.

Better parts can sometimes translate into better sound. And sometimes not. But simply arranging for better parts to be installed does not make for a better mod or a better modder. The modder needs to be intimately familiar with each particular circuit or piece he's trying to mod - otherwise it's kind of a crapshoot at best (and possibly an expensive one). An expensive modder is not necessarily a respected modder. So take all that slowly. But, I do agree with Grannyring's post.

They can most certainly in the hands of a skilled craftsman that understands the overall design case by case, but no guarantee in general. The devil is all in the details.

I would expect a difference in sound with the specific combo the OP relates, most likely for the better, but only if done well by someone who really knows what they are doing.

Parts are just parts. Its what is done with them that always matters.

I would recommend that for whatever cost might be involved for any particular custom mod, especially pricey ones, options to replace or upgrade to different well received high value gear be considered as well. Sometimes better results can be achieved more easily replacing rather than tweaking. All surgeries usually come with some amount of risk.