I don't remember if some later Subaru's need a fuel return, or if that would apply to a 2004 model...
If injectors are a rail of 4 as is usual with BRC, pipe lengths to spuds will be long on the flat 4. This usually has more of a negative effect at low rpms than at high rpms but can be detrimental to drive-ability, especially on a turbo, at any rpm.
Does this Subaru have the 'extra throttle flaps near the intake valves' setup that helps with throttle response? If so it is necessary to fit spuds below those flaps.
Tip in/out settings are similar to acceleration/deceleration enrichment/leaning, ideally not employed.
BRC Sequent could mean Sequent/24/24MY07/56, etc. There are some key differences in terms of calibration abilities and how they're set up - Pre MY07 Seq24 systems are not capable of sequential fuel changeover and wiring is unusual, pre Seq56 systems only have manifold pressure sensor connected during calibration during which time the system learns gas pressure versus manifold pressure versus Pinj etc, then the manifold pressure sensor is disconnected.. Would struggle to get any re-calibration based on incorrect original manifold pressure readings correct - so for complete re-calibration of pre56 the installer must have and use the manifold pressure sensor, rather than assume some supplied file contains correct data. In addition, supplied files contain injection methodology data with certain functions (e.g. extra injection filtering) pre-configured/enabled/disabled. Seq56 is better, Plug N Drive better still. Older spec systems generally a fair bit cheaper than the more recent BRC stuff and not always as appropriate for modern/demanding engines. With BRC, injectors with correct spec must be chosen from the outset as you can't change nozzles etc on BRC injectors... and when selecting injectors you cannot always go on charts which suggest an injector spec based purely on bhp per cylinder. 280Bhp will need BRC's big reducer.
I don't remember being unable to arrange a conversion date for a Subaru turbo. I don't often fit BRC and would have advised a different system but if the customer still wanted BRC I would have advised Plug N Drive, or maybe we could have come to some arrangement where I first tried one of the second hand Sequent24/56 systems I have on the shelf here. If I'd converted it there would be no issues but it's a bit late for that.. Still, if it comes here I'll definitely identify the issues - and sort it if possible given fitted components, or advise different components in which case would sort it for sure if tasked with doing so.
The LPG bits I fitted on your car would give excellent results on this car if fitted and calibrated correctly Rich
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
2 miles A1, 8 miles M62, http://www.Lpgc.co.uk