No problems converting it but you may want to read the following threads and take care when choosing an installer
I'm not saying I'm the only one who gets good results on these models because I know that's not true, but there may be plenty of installers that would come across as all confident but then not deliver the results.http://www.lpgforum.co.uk/viewtopic.php?f=28&t=14176http://www.uklegacy.com/forums/index.php/topic/143724-jdm-spec-b-lpg-help/
Though I haven't converted a twin scroll model (which yours may not be, but the vehicle that is subject of above threads is), I see no reason why it should prove any more difficult than other Subaru turbos of which I've converted plenty that run just as well on LPG as on petrol, the most recent last week http://www.lpgforum.co.uk/viewtopic.php?f=27&t=14211
I will more than likely end up correcting the problems with the vehicle that is the subject of the top two links.
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