Hand made Boost Pedal 2n5089 - True Bypass.
Won't color the sound or add Distortion or break up. I worked at making a boost pedal that would just boost the signal and I believe this pedal will help you if that is what you are after.
The most popular is the 2n5088. It is smoother than the 5089 but not a huge difference just a little more bite with the 5089 (I use the 2n5089 on country tunes). I leave the 5088 on all the time because it fattens every thing up and gives that AC/DC and Keith Richards sound with solid state amps (I use my volume control on my guitar quite a bit like Stevie Ray Vaughn uses his). I use a Randall/Marshall solid state set up. The pedals give them more driven clarity and I don't have to fool with tubes by using my volume control on my guitar. I set my master knobs on both of my amps at about 3/4 and I use the clean channel at about 1/4. But I turn the 5088 off and switch to the 5089 for country. So really either one will give a significant boost and sound similar. You would have to play both quite a bit to tell the difference but there is a difference once you play both a lot. I do have several people that use the boost on tube amps as well but primarily I made the boost for solid state amps set on clean channel. I prefer to use external floor pedals for overdrive, distortion, chorus, delay etc. My amp stays at the same setting all the time and I use my volume on my guitar to push and back off my amp.