Century, Denio, Boston pedals i think are moddable.
Behringer uses SMD. tiny little parts. moddable din. that is if you have robot-precise hands
kaya naman siguro. with Behringer kasi it's more "use it if you like it".
i used to have GTX pedals (Boston Eng'g. family) but sold/traded both. Behringer lang ang meron sa board ko from the above pedals mentioned. the buffers are pretty fine i think.
or better yet, ask Sir BAMF. he does many things to these inexpensive gems!