I think it may have a problem with the Corporation tech (as it's added by CBP), which may keep its basic value (depending on how the mod is implemented).
I have done something similar myself :
I play in Epic speed but have modified the XML file changing the tech base costs :
The file is :
MODS\(2) Community Balance Patch\Balance Changes\Tech\TechCostChanges.sql
Here is what I changed it to :
-- Change Tech Costs (from CEP):
UPDATE Technologies SET Cost = 40 WHERE GridX = 1; -----50----35
UPDATE Technologies SET Cost = 80 WHERE GridX = 2; -----75----55
UPDATE Technologies SET Cost = 200 WHERE GridX = 3; ----125---105
UPDATE Technologies SET Cost = 400 WHERE GridX = 4; ----225---175
UPDATE Technologies SET Cost = 800 WHERE GridX = 5; ----325---275
UPDATE Technologies SET Cost = 2000 WHERE GridX = 6; ----625---485
UPDATE Technologies SET Cost = 3000 WHERE GridX = 7; ----825---780
UPDATE Technologies SET Cost = 4000 WHERE GridX = 8; ---1300--1150
UPDATE Technologies SET Cost = 6000 WHERE GridX = 9; ---1800--1600
UPDATE Technologies SET Cost = 8000 WHERE GridX = 10; ---2400--2350
UPDATE Technologies SET Cost = 11000 WHERE GridX = 11; ---3200--3100
UPDATE Technologies SET Cost = 14000 WHERE GridX = 12; ---4400--4100
UPDATE Technologies SET Cost = 19000 WHERE GridX = 13; ---5400--5100
UPDATE Technologies SET Cost = 25000 WHERE GridX = 14; ---6600--6400
UPDATE Technologies SET Cost = 32000 WHERE GridX = 15; ---7800--7700
UPDATE Technologies SET Cost = 40000 WHERE GridX = 16; ---9000--8800
UPDATE Technologies SET Cost = 50000 WHERE GridX = 17; --10000--9500
UPDATE Technologies SET Cost = 60000 WHERE GridX = 18; --11000--NEW!
the "Cost = 50000" are the new costs, the "--10000" is tyhe usual cost as per CBP, the "--9500" is the vanilla cost.
Those costs are then multiplied by the gamespeed modifier and all things like that.
You shouldn't put something much higher than 60,000 (at least if you play in Epic), as higher numbers (or at least 100,000 in Epic) are not handled correctly by the game engine (you get an overflow and the cost become negative).
If you use this method, don't forget to go in the coporation tech fiel to change it as well :
MODS\(2) Community Balance Patch\Modular Elements\Corporations\CorpTech.xml
7th line. I replaced the cost with : "<Cost>11000</Cost>", as it seems to match with the previous table.