We hadnt planned on making shirts with that designs... you can get L4 shirts from Farmer (though they are just black and white). We didnt want to encroach upon his already established sales. We had considered some printed stickers with just the engine though.
Yes, S30 designs are in the works. We are contemplating making a design similar to the 510 one we released where it shows side profiles of each model... I dont know how well that would work as, at least to me, all S30s look the same with very minor differences. Would look weird with the same design three times in a row.
We are always open to customer feedback and suggestions for designs so if there are people that have specifics for a model, shoot us a PM and we can see what we can work out.