ok im split between two choices. its either the milltek or mongoose flexi and the price of the mongoose makes me want it more but the diameter of the mongoose is slightly smaller so i dont know if this will affect power much. got a few prices so any advice would be much appreciated.

http://froogle.motorsportworld.co.uk/framefix.asp?PID=998986&ProductCode=SSXFD015

http://www.grahamgoode.com/website/parts.php?website=19&item=SSXFD015

http://www.larkspeed.com/index.pl?a=i&k=s&p=MONFD0251

go for milltek,alot of people from other forums have had a mongoose for 5 6 months and they have broke

Neither... save a little more for the manifold bud and then you'll see a better power increase!
The manifold also includes the flexi section!

Is it worth going for the manifold if I'm not changing the exhaust??

No idea, but did I read somewhere that the new manifold has a different flexi on it anyway?

But if I was to fit a manifold then surely to gain full benefits from it, I would need to fit full exhaust system and have a remap which I'm not bothered about doing.

If you can afford the branches then get them! The stock exhaust setup is very good. Only if you get a properly set up exhaust + manifold you will make about 4 - 5 kw extra over the flexi with a stock exhaust. Same with the NM's.

Ha I said I'd never touch my
Supercharged 20months later...

Get a Full Milltek system and never look back mate