Expense of a BMW

[Mad_Maxima]

My friend was looking into buying a BMW, maybe a Z4 or M3, but he doesnt really know much about BMW's, he's a Honda guy.
So he was wondering if modifying one cost about the same as, say a S2000. I've heard Dinan is a good supplier for BMW performance parts, but that they are really expensive.
So are there any other suppliers that sell bimmer parts for Honda prices?
Like how much would a turbo cost to install? Would the basics like headers intake and exhaust cost what you would pay for a Honda, or does the BMW title also increase the price?
Thanks in advance for any help.

[DinanM3_S2]

Following the simple rule of supply and demand, tuning BMWs will always be more expensive then modifying Hondas. There are fewer BMWs out there, and fewer people tuning BMWs out there, thus prices are higher because fewer parts are made.

Dinan is a very good source for performance parts for BMW because they are reliable, and backed by warranty. Because they are backed by warranty, Dinan products are exceptionally expensive. They do alot of R&D before they release a product, so they are pretty top of the line. The downside to Dinan besides price is gains. Its hard to get power out of BMWs safely, especially the higher strung M3s. Dinan doesn't get the power gains per dollar that many of the other tuners get. If you have the money to spend, and intend to use a BMW as a daily driver, Dinan is a good route. If you are concerned with racing and not so much with reliability, I would look elsewhere. I use Dinan parts on my car.
www.dinancars.com

Other major BMW tuners include, Turner Motorsports (http://www.turnermotorsport.com/html/index.asp), Active Autowerke (www.activeautowerke.com), Hartge (http://www.hartge.de/html/indexuk.html), Alpina (not sure if you can get their products in the US), AC Schnitzer (http://www.acschnitzer.com/), and DA Motorsports (http://www.da-motorsport.com/default.asp).

The only companies that I know of that works with turbochargers for BMWs are Active Autowerke and DA Motorsports. Active Autowerke and Dinan both make supercharger kits. Hartge deals alot with engine swaps from bigger BMWs (like the M5) into smaller ones.