Danf1275

Filled my 07 WRX up over the weekend, with usual Tesco 99RON fuel, and it definitely feels smoother and more powerful afterwards. Tank was almost empty - fuel light was on.

One thing I did notice was hissing noise when cap came off - hard to tell if pressure in tank was less or greater than ambient.

Car is stock other than Haywood and Scott catback, forge wastegate actuator and opensource remap (gabedude).

Is this normal or a symptom of something else? Search function didn't reveal anything.

Cheers.

skins

hissing noise is fine mate, mine does is all the time when the fuel is very low and i open the cap

TeddyTaylor

Funnily enough when i fill my tank with usual Tesco 99 first few miles just seem really smooth and responsive. Weird eh!

jimbojones1000

Ive always though my cars felt quicker when i'd just filled them up, thought it was just me, dont see how it can be though.

barnshaw

iTrader: (1)

sounds silly but although you have a heavier tank from filling up the fuel is probably at its best and has its best octane properties, also it is probably at its best temperature, thats my theory anyway lol. but yes i notice after filling up it seems a bit better