I've never seen specific claims from Milltek for any of their systems - be they full or cat-back. The ED30 development one (full system) achieved 18bhp over standard exhaust on the rolling road. 
Really?! I'll have that thankyou 
As long as it is nice and well behaved like the standard exhaust. I hate loud aftermarket exhausts. 
Think I'd have to hear one in action before ever deciding to put it on otherwise it might end up for sale here at a cheap price 
Exactly! i already feel like a bit of a chav when I accidentaly rev the engine a little too much. The exhaust sounds just fine as it is.. more power? Yes! More noise?? No thanks 
....I wish I had £1 for every time I've explained Millteks.
- Construction of ALL Millteks is high-grade Stainless Steel throughout and they are guaranteed for however long you own your car.
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Without a remap, bhp gains are insignificant (about 5 bhp) but there will be improved throttle response.
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With a remap, bhp gains may contribute 15-20 bhp, especially with the Hi-flow+Downpipe aka Turbo-back.
- Resonated version is only slightly 'noisier' than stock.
- Non-Resonated version is only slightly louder again by a similar increment/difference.
- Milltek exhausts sound sporty but never 'boy-racer' and only louder when engine is working harder. In my opinion the Mk5 cabin is far too soundproofed and hearing what your engine is up to is a real driving aid. For example, when my plugs needed changing I could hear it was an ignition problem.
