I wouldn't worry too much about using the 15mm ones that come with the kit as the inside of thehockey puck is way smaller than 15mm. Using the ones you have won't be restrictive at all.
If you do want to try a 19mm adapter, try this http://www.ebay.co.uk/itm/BRASS-Male-BSP-Taper-Hose-Tail-Fitting-Silicone-Fuel-Water-Air-Gas-Pipe-BSP-UK-/271178314986?pt=LH_DefaultDomain_3&var=&hash=item3f237cb4ea
Also are you sure about it affecting the MAF reading?
Quote from: mar_k on 10 May 2013, 17:40Also are you sure about it affecting the MAF reading?pull a pipe off your catch can and see how your engine runs!if there is a leak between the throttle body and maf it`ll run like a sack of sh!t. people who vent to atmosphere plug the hole in the tip fir de hockey puck