circumstantial evidence, but in my 110 I did a shallow dive to match speed of TU-2's at 23k and hit the WEP. 3 sectors later I had only gained .5k on him. Hitech's charts show I should have a top speed of about 368 in level flight vs his ~325. I think those empty tubes hurt my speed quite a bit. I wish I had saved the video see my actual top speed, if I remember right it was around 330.
I was able to catch him when he turned to land, but a base ack got my engine and the punk ended up finding me again 3 sectors away NOE and shot me down
Edit: Just did some actual testing.
In offline practice I took a 110 with 25% fuel and rockets to 2k and leveled out. Was able to get to 287mph IAS, then fired my rockets and was able to get up to 295mph.
I then took off without the rockets and acceleration was much faster after getting to 2k and was able to get to 310mph. I probably wont be taking rockets anymore as a 15mph penalty on the deck is pretty brutal.
And just finished some A5 testing. 308 with rockets, 311 after firing, and 328 clean. 50% fuel.