You will gain a definate HP upgrade by just changing your exhaust and down pipe. A larger 2.5 cat back exhaust system will give you a nice jump. The turbo will spool up faster and you will have less back pressure. I purchased a Walker Turbo Dynomax muffler and had a local muffler shop install it. Total cost $186.00 installed with muffler. The muffler was $36 including shipping.(www.summitracing.com) I had a 89 744tic+ with an M46. After that install I noticed a HUGE difference.

Second I would do the APC, and Terminal 11 trick. I hear that works well on the older Turbo cars. Go to TurboBricks.org and do a search on their archives. That group is alot more intense when it comes to modifications. Get on their mailing list and you will learn alot from their posts. Make sure you search their Archives first.

Make sure you have your car at factory OEM specs before you do any upgrades. This means Valves, timing, belts, fluids etc. must be changed and adjusted or your upgrades are pointless, and might cause major damage..