Big Turbo Inlet 450ish bhp - free on a LT car .
Small Turbo EEC 500ish bhp - £100ish
RS500 Sierra 600ish bhp (without mods) £1 - 1.5k depending condition
Sweedish - not found limit yet, most seen so far is 737bhp £380
Mountune "Same as Rainbirds" 630ish bhp £3,200 new £1.5k + second hand*
MIS "Same as Reylands" not found limits yet, but the Norwegians have one running an "alleged" 920bhp. However, be aware that this is on a single butterfly, not the individual TBs that Martin has converted his to. £1.5k second hand, similar price to the Mountune one when it was new. But that is the standard item, not the one where Martin has incorporated Jenvey ITBs into it.*

*Please note that an ITB set-up requires T6 to run the multi-maps required, which adds and additional £2k+ for the required ECU and loom.