I have attached a chart showing the results of a cam only change in a stock TC88. OP, take a look and pick a cam assuming you are staying stock. I did not do the testing; not a tuner but found these test results and kept them. As you can see, the customer that paid for the testing selected the 509 but you may read the results differently; I would have selected the Andrews 48 which I had forgotten about as I didn't recall your bike is an '05 with the beehive springs that wil accommodate the higher lift of the 48. The customer did have a better exhaust system that the B&H Long Shots which you might want to sell down the line and replace with a better system.

The SE204 has a nice lumpy idle but, as several have pointed out, it is soft off idle but nice in the mid range because it is a mid range cam.

I am just going to throw out another option to overcome that early lag; one that isn't talked about much these days as it is specific to the earlier models, say pre '07 which nobody is really interested in any more. However, back in the day this conversion was considered a performance modification with no engine work and was often referred to as a "poor man's big bore kit" because the bike was so much quicker. The option was to change primary gearing from 25/36 to 24/37. '99-'01 primary gearing in carbed touring models was 25/36 but the primary gearing in the EFI models was 24/37. The 24/37 comp sprocket (PN 40269-A)and clutch basket (PN 37846-99A) are "obsolete" as OEM parts and hard to find.The clutch basket PN does include the Koyo bearing and clutch basket retaining ring. At about $475, if you can find the parts, a more expensive option than a simple cam change but really makes for a quicker bike. Down side, maybe, is a drop of about 200rpm at 70mph;2900 instead of 3100.

As I previously stated, the HD Stage II "legal" flash is not a tune; a bit of fuel across the rpm range and an increase in rev limit; that's it. If I thought a dyno tune would get you the lower end improvement you want from the 204s, I would recommend it. At this point, a cam change and a dyno tune might get what you want. I also suggest that you look into the primary gearing change outlined above; it will be a different bike.

 

Deleted; double post.

 

I just put 510 gear drive cams in my bike. So far I am pleased, much better than stock.

 

OP, go back and read this thread. See how many members pointed you to the S&S 509 cam for TC88. They know what they are talking about. I have the 509 and can vouch for it. Good tune and it pulls well of idle and down the road. If you want to go a different bore size, that's a different story.
hth

 

I'm a fan of a gearing change and cams more in line with the 204s myself. Gives you the best of both worlds. Plenty of get up off the line and power up top that doesn't die prematurely.

 

If we're looking at a budget improvement: If the 25/36 to 24/37 primary change 'eliminates' the OP's lag issue, wouldn't a final drive counter shaft pulley change from 34 tooth to 33 tooth effectively offer the same result (for even less money?)

 

As stated a better tune will help. A better exhaust system will help also. With those cams, stock head pipes with un modified SE mufflers will be better. You can try and add a little back pressure to the current setup if you like playing around.
Add:
Being a 5 speed, I wouldn't re-gear it unless you ride 2 up and no freeways..

 

If I recall correctly, a 1 tooth change of the finals does not gain as much as 1 tooth on the primary. I could be wrong tho. Then there's the belt change that's needed that would need to be factored in the cost too.
There's a good sticky on this whole subject somewhere I think.

 

He does ride 2up. The Rush slip ons and stock head pipes do well on the bottom too. They would do even better with the 1.75" baffles available for them rather than the 2" I ran in them and be more suitable to a stock 88" anyway. Maybe even add TTIs?
If not for the fact he rides 2up, I would go this route but 2up probably not.

 

The OPs tranny sprocket is not 34T; final drive is 70/32. To achieve the same effect, the OP would have to drop the trans pulley to 30T which would very likely require a belt change. If a 33T trans pulley is available, it would help the lag issue and 70mph would add about 100rpm which woulld certainly be more tolerable at freeway speeds. A secondary change would also require a speedo modification whereas a primary change would not.