Guessing your getting this all from the Internet as the Revo website states aprox 35-50bhp after a map, Darkside or any other company (which probably wouldn't state, but if they were) stating more than 150bhp on a 115bhp B7 is delusional without injectors, if your looking at Darkside's site I can only assume you mean this car
Audi A4 Avant 1.9 8v TDI (AWX)... which has GTB2260VK turbo with 130bhp injectors
. Never heard of James Renshaw but after a quick google I assume he owns a B8 which will have a different engine and in terms of the noise it made... haha... sounding like a v8 doesn't matter unless it had v8 figures. A decat will undoubtedly make the turbo spool quicker but it's not advisable on the 1.9tdi's turbo as it's small and will overspool fairly easily. If you want realistic performance figures with mods on this engine then look at some of Darkside's other cars as they have made a fair few decent ones although as I say they will all have injectors and turbo's on top, tdi club's good too and there's also a fair few people in the b5 section with decent builds. As I say feel free to prove me wrong but yours will undoubtedly still hit around 150bhp. For the record I own a 130bhp B6 with a BV43 pushing an easy 200bhp, clutch is slipping ridiculously so it'll be getting Sachs organic clutch and staying dual mass which is recommended as single mass destroys 5 speed boxes. That would be my recommendation if you had turbo and injectors but with what your doing I'd say wait and see if it slips then if so replace with the original unless your going to do anything worthwhile in which case go for the same clutch as me for (A REAL) 200bhp or single mass and 6 speed for anything more.