The brakes were an utter joke on my Secteur Sport when I bought it, it was pretty dangerous. I read on here and a lot of people had upgraded to 105 calipers and pads. I was skint so just upgraded the pads to Clarks CPS240 with existing Tektro calipers. This made a huge difference. However a couple of weeks ago I noticed
Wiggle were selling off 105 5600 front calipers for £24.99. So I bought one, when I removed the Tektro caliper, I held it in one hand and the new 105 in the other. I could tell no difference in weight. I put the 105 caliper on but swapped the Clarks pads over so that I could correctly compare the Tektro versus the 105 caliper. After 2 weeks I cannot tell any difference in braking performance. I am pleased that I only paid £25 for it, I guess Shimano 105 does look nice written on it compared to the plain Tektro caliper, but that is about all I can say about it. Then again the Tektro caliper looks identical to the 105, except maybe a slightly smaller spring so I really do not know what I was expecting to be honest.
If I was you I would just change the pads.