Seraga,
I have already upgraded the exhaust to a Quicksilver, do you have any ideas about brands for (or more importantly who sells) a high performance intake for the car?
Thanks
Faraz
Sure, I will try to give you some idea about the subject, though you should not listen to me alone before going from theory to practice.
One of the reasons that the DBS has more high end power than the DB9 is that there is a valve that opens at higher RPM to allow more air in and for the engine to breathe better. It is feasible to modify the intake system to DBS spec, and it was done by some companies before (I think specifically Aston Works Service and or Edo Competition would be able to do a conversion). The cost of that would be quite high, but it would be the most reliable way of doing an upgrade of the intake system.
This would then call for any alternatives to upgrade the intake... most obvious one to me would be to install a pair of freer filters compared to the original ones. If you are/will be getting the remap at Paramount performance, I think they can install the cold air filters as well, however if you would want to get the remap done by another company, I think K&N is (one of) the most popular options available out there. Because these systems allow for less resistance in air flow into the engine, they also allow for a greater range of debris, so these filters must be changed more often.
Also, your DB9 is of the first generation (2004-2009). These cars received a technical update in 2009, in which they increased the compression ratio of the engine from 10.3:1 to 10.9:1 by revising (milling off) the head...
If you do not plan on putting any sort of forced induction on your car (and you have access to a well equipped machine shop), you could mill the cylinder head down by about 0.5 mm... This and buying some gaskets would give you the "engine part" of the technical upgrade, ie teh extra 20 bhp and 20 lb-ft torque they have on the new DB9s.
Lastly, less restrictive catalytic converters might help you further improve the exhaust system (those can be purchsed off paramount), since you already have tuned the car for high end power.
I guess then the remap will come.
Hope this helps
Lastly, there is a member "Squid" on this forum. He has done a lot on his DB7 GT and is very knowledgeable on tuning. You can PM him with these questions as well, and I think he will help a lot.